The pictures to the right, show two different models
of the atom. Type in the letter of your answer.
Which model best represents Dalton's atomic
theory?

Answer:

0.756 J

Explanation:

Temperature change (delta T) = 0.855 degrees Celsius

Mass of water (m) = 0.2067 g

Specific heat capacity of water (c) = 4.28 J/g degrees C

Heat added = m * c * delta T

= (0.2067 * 4.28 * 0.855) J

= 0.756 J

Answer:

Zinc Carbonate

Zinc Nitrate

Explanation:

Answer:

C) Liquids and gases

Explanation:

The correct answer would be liquids and gases.

The molecules of liquids and gases move randomly when held in a container. The random movement causes a collision between the molecules of the liquids/gases and between the walls of the container, creating pressure in the process. This is unlike the molecules of solids that vibrate about fixed positions.

Hence, the correct option is C.

Answer:

F

Explanation:

"The mass of the products is equal to the mass of the reactants" is true about the principle of the conservation of mass.

So, option f is correct one.

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Answer:

5010J

Explanation:

The following data were obtained from the question:

Mass (m) = 15g

Heat of fusion (ΔHf) = 334J/g

Heat required (Q) =..?

The heat energy required to melt the ice can be obtained as follow:

Q = m·ΔHf

Q = 15 x 334

Q = 5010J

Therefore, the heat energy required to melt the ice is 5010J.

Answer:

They all have the same number of molecules or atoms which is 3.011*10²⁴ molecules or atoms.

5 moles of O = 3.011*10²⁴ molecules or atoms

5 moles of N = 3.011*10²⁴ molecules or atoms

5 moles of MgCl2 = 3.011*10²⁴ molecules or atoms

5 moles of C2H3NO = 3.011*10²⁴ molecules or atoms.

Explanation:

a)

5 moles of O = ?

1 mole of any substance is equal to Avogadro's number which is equal to 6.022×10²³molecules or atoms

From the question above,

5 moles of O = 5 × 6.022*10²³ = 3.011×10²⁴atoms or molecules.

b)

5 moles of N

From the same principle or fundamentally stated fact above,

1 mole of any substance = 6.022*10²³molecules or atom

5 moles of N = 5 × 6.024

2*10²³ = 3.011*10²⁴atoms or molecules.

c)

5 moles of MgCl₂

Same principle we used in a and b,

1 mole of any substance = 6.022*10²³ atoms or molecules

5 moles of MgCl2 = 5.0×6.022*10²³ = 3.011*10²⁴ atoms or molecules.

d)

5 moles of C₂H₃NO = ?

1 mole of C₂H₃NO = 6.022*10²³molecules or atoms

5 moles = x molecules or atoms

x = 5 × 6.024

2*10²³ = 3.011*10²⁴ atoms or molecules

What this proves is that no matter the compound, molecule or element, as long as they have equal amount of moles, they'll have the same number of atoms, molecules or particles.

Answer:

a. 3.011x10²⁴ atoms of O in 5 moles.

b. 3.011x10²⁴ atoms of N in 5 moles.

c. 3.011x10²⁴ atoms of MgCl₂ in 5 moles.

d. 3.011x10²⁴ atoms of C₂H₃NO in 5 moles

Explanation:

A mole is defined as the number of atoms in exactly 12.000g of ¹²C.

This number is equal to 6.022x10²³. That means 1 mole is equal to 6.022x10²³.

Thus:

a. O . 5 moles of oxygen (An atom) are:

5 moles O ₓ (6.022x10²³ atoms of O / mole) = 3.011x10²⁴ atoms of O in 5 moles

b. N . Also, 5 moles of nitrogen are:

5 moles N ₓ (6.022x10²³ atoms of N / mole) = 3.011x10²⁴ atoms of N in 5 moles

c. MgCl₂ . Magnesium chloride is a molecule. Again, 1 mole of MgCl₂ contains 6.022x10²³ molecules and 5 moles are:

5 moles MgCl₂ ₓ (6.022x10²³ molecules of MgCl₂ / mole) = 3.011x10²⁴ atoms of MgCl₂ in 5 moles

d. C₂H₃NO. 5 moles of C₂H₃NO are:

5 moles  C₂H₃NO ₓ (6.022x10²³ molecules of  C₂H₃NO / mole) = 3.011x10²⁴ atoms of C₂H₃NO in 5 moles

As you can see, number of molecules of 1 mole doesn't depend on the nature of the substance.

Answer:

A cation that has a smaller radius than the atom.

Explanation: when electrons are removed from the outermost shell of a calcium atom, the atom becomes a cation that has a smaller radius than the atom.

When electrons are removed from the outermost shell of a calcium atom, the atom becomes  a cation that has a smaller radius than the atom. Therefore, the correct option is option D.

Atom, the smallest unit of matter that may be separated without releasing electrically charged particles. It is also the smallest unit of matter with the characteristics of a chemical element. As a result, the atom is indeed the fundamental building component of chemistry.

The majority of the atom comprises empty space. The rest of the structure is made up of a positive-charged nucleus of neutrons and protons surrounding by a cloud of electrons with negative charges. In comparison to electrons, the lightest energized particles in nature, the nuclei is small and dense. When electrons are removed from the outermost shell of a calcium atom, the atom becomes  a cation that has a smaller radius than the atom.

Therefore, the correct option is option D.

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Answer:

Here's what I get  

Explanation:

Sublimation is the conversion of a solid directly to a gas, without passing through the liquid state.

It occurs when the molecules of a solid have absorbed enough heat (kinetic energy) for some molecules to overcome the attractive forces of their neighbours and escape directly into the vapor phase.

One substance that sublimes at room temperature and pressure is CO₂ (dry ice).

Naphthalene is a substance that sublimes at room temperature and pressure.

Sublimation is defined as a process in which solid converts into gas directly without converting into liquid.

In the sublimation process, the reaction is an endothermic reaction, as the chemical bonds between molecules are broken down in order to release them into the air. Therefore ,the energy is released and so it is an endothermic reaction.

The heat or energy required to change the state from solid to gas is called the enthalpy of sublimation .Generally, it is expressed as KJ/m o l. Sublimation only occurs at pressures and temperatures .

Hence , Naphthalene is a substance that sublimes at room temperature and pressure.

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Answer:

a

Explanation:

Answer:

Replication

Explanation:

In science, the work of a scientist is regarded as authentic if other experts in other places can follow the same steps as he/she claimed to follow and arrive at the same result.

For example, a scientist in California, United States of America may carry out a research and publish his findings. Another scientist in Christchurch New Zealand following exactly the same procedure is expected to arrive at the same results as the original researcher if there were no errors in the work.

However, where there are disparities in results, the scientist in Newzealand may discover errors that were unknown to the original researcher in the united States. The New Zealand scientist was carrying out a process known as 'replication'. That is, repeating a scientific research in order to obtain the same results thereby validating the research.

Answer:

the 3rd one (0.01 cm the one selected already)

Explanation:

copper wire isn't excessively big, and it wraps around the pencil because its malleable. I think that the most accurate would be 0.01 cm

Answer:

A. C(s) + O2(g) → CO2(g) + 393.5 kJ

Explanation:

The formation of carbon IV oxide (CO2) is an exothermic process. n exothermic process is a chemical process in which heat is evolved. Speaking in lay man's terminology, heat is one of the 'products' of the reaction. This implies that heat is evolved by the process.

The formation of CO2 is always a combustion reaction where heat is evolved or released by the reaction system. Hence the reaction could be shown as;

C(s) + O2(g) → CO2(g) + 393.5 kJ

This implies that 393.5 kJ of energy is released in the reaction in the form of heat. Hence the answer given in the answer box.

Answer: C(s) + O2(g) → CO2(g) + 393.5 kJ

Answer:

domain bacteria

Explanation:

Salmonella and E. coli are same in the sense that they are both bacteria,

Answer:

B

Explanation:

Answer:

true

Explanation:

polarity of the molecules increased with electronegatiy it's true

Answer:

Because electronegativity of Oxygen is higher than electronegativity of Carbon.

Explanation:

The electrons in a bond between carbon and oxygen, C-O, closer to the oxygen atom than the carbon atom because electronegativity of Oxygen is higher than electronegativity of Carbon.

Answer:

1. 0.56 mole of electron.

2. 0.28 mole of Co .

3. 16.52g of Co.

Explanation:

The following data were obtained from the question:

Current (I) = 15A

Time (t) = 1 hr = 1 x 60 x 60 = 3600secs

Next, we shall determine the quantity of electricity, Q flowing in electrolyte. This is illustrated below:

Quantity of electricity (Q) = current (I) x Time

Q = It

Q = 15 x 3600

Q = 54000C.

1. Determination of the moles of electrons used to electrolyzed the solution. This is illustrated below:

96500C = 1 mole of electron

Therefore, 54000C = 54000/96500 = 0.56 mole of electron.

Therefore, 0.56 mole of electron was used to electrolyze the solution.

2. Determination of the number of mole of Co produced at the cathode. This is illustrated below:

At the cathode:

Co2+ + 2e —> Co

From the balanced equation above,

2 moles of electron produce 1 mole of Co.

Therefore, 0.56 mole of electron will produce = 0.56/2 = 0.28 mole of Co.

Therefore, 0.28 mole of Co is produced at the cathode.

3. Determination of the mass of Co produced at the cathode. This can be achieved by doing the following:

Molar mass of Co = 59g/mol

Number of mole of Co = 0.28 mole

Mass of Co =..?

Mass = mole x molar mass

Mass of Co = 0.28 x 59

Mass of Co = 16.52g

Therefore, 16.52g of Co is produced at the cathode.

Answer: 2.5 grams

Explanation:

Expression for rate law for first order kinetics is given by:

[tex]t=\frac{2.303}{k}\log\frac{a}{a-x}[/tex]

where,

k = rate constant

t = age of sample

a = let initial amount of the reactant

a - x = amount left after decay process  

a) to calculate the rate constant:

Half life is the amount of time taken by a radioactive material to decay to half of its original value.

[tex]t_{\frac{1}{2}}=\frac{0.693}{k}[/tex]

[tex]k=\frac{0.693}{2years}=0.346years^{-1}[/tex]

b) to find amount left after 4 years

[tex]4=\frac{2.303}{0.346}\log\frac{10}{a-x}[/tex]

[tex](a-x)=2.5g[/tex]

Thus 2.5 g of cesium would remain from a 10 g sample after 4 years

Answer:

Volume=mass in g /density

Answer: 40cm^3 or 40ml

Explanation:

[tex]Density=\frac{mass}{volume}[/tex]

so 5=200/V

V=200/5

V=40cm^3

Answer:

Alcohol

Structure: Alcohols are organic molecules assembled from carbon (C), oxygen (O), and hydrogen (H) atoms.

Property: The Boiling Point of Alcohols. Alcohols generally have higher boiling points in comparison to other hydrocarbons having equal molecular masses.

Aldehyde

Structure: DescriptionAn aldehyde is a compound containing a functional group with the structure −CHO, consisting of a carbonyl centre.

Property: The polarity of the carbonyl group notably affects the physical properties of melting point and boiling point, solubility, and dipole moment.

Ketone

Structure: A ketone is a functional group with the structure RC(=O)R', where R and R' can be a variety of carbon-containing substituents.

Property: Ketones are soluble in water but their solubility decreases with increase in the length of the chain.

Fatty Acid

Structure: a fatty acid consists of a straight chain of an even number of carbon atoms, with hydrogen atoms along the length of the chain and at one end of the chain and a carboxyl group (―COOH) at the other end.

Property: Fatty acids are solid at room temperature, while unsaturated fatty acids are liquid.

Ether

Structure: a class of organic compounds characterized by an oxygen atom bonded to two alkyl or aryl groups.

Property: An ether molecule has a net dipole moment due to the polarity of C-O bonds.

The functional group associated with ethanol is -OH, the aldehyde is -COH, the ketone is -CO, the fatty acid is -COOH, and ether is ROR.

The functional groups have been the atoms that have different constituents and properties with respect to other groups.

The functional group associated with the following groups has been:

The functional group associated with ethanol is -OH, the aldehyde is -COH, the ketone is -CO, the fatty acid is -COOH, and ether is ROR.

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Answer:

D

Explanation:

Atomic radii decrease slightly and then start to increase.

Atomic radius of transition metals from left to right increases slightly then decreases. Thus it is not following the trend as for other periods. Hence, option c is correct.

Transition metals are d-block elements in periodic table. starting from group 3 to group 12. Transition metals are called so because they are in between gases and metals in periodic table.

All transition metals shows varying oxidation states.  For example, iron Fe shows +2 and +3 and copper shows +1, +2 and +3.  Transition metals are malleable, ductile and are good conductors of heat and electricity.

From left to right in a row in periodic table, the atomic radius decreases and electronegativity increases. However, this trend is not systematic in the case of transition metals where, the atomic radii increases first and then decreases.

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Your question is incomplete, but your complete question probably was:

Which is true of transition metals when moving from left to right on the periodic table

The d sublevels are not filled across the period.

The cation radii become larger across the period.

Atomic radii increase slightly and then start to decrease.

Atomic radii decrease slightly and then start to increase.

Answer:

C.

Explanation:

pH > 7, basic, so pH = 9  is basic.

When solution is basic, it will turn phenolphthalein pink.

A piece of lithium metal is added to a beaker that contains water and phenolphthalein. Using what you know about the properties of bases, choose the best explanation for what you observe.

Answer:

The phenolphthalein is turning pink because a base is forming.

Answer:

It is decreasing the temperature of the reactant mixture.

Explanation:

Just took the test

In order to decrease the number of collisions and energy of reactant molecules, the temperature of the reactant mixture would need to be decreased as well.

The temperature of reactants is proportional to the average kinetic energy of the molecules of the reactants.

Also, the higher the average kinetic energy of the reactant molecules, the higher their chances of colliding and reacting to form products.

Thus, in order to decrease their energy and collision frequency, the temperature of the reactant mixture needs to be decreased.

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Answer:

basic solution.

Explanation:

has a pH of 12.

it turns clear indicator pink.

it contains hydroxide ions which conduct electricity

Answer:

Yes

Explanation:

Yes, A substance can be a lewis acid without being a Bronsted-Lowery acid because there are some substances which cannot donate protons(Bronsted-Lowery acid) but can accept a pair of electron.

For Example:

Let us take the example of BF₃

BF₃ contains no proton so it is not a Bronsted Lowery Acid

However, BF₃ has an incomplete octet with 6 electrons. It needs an electron pair to complete its octet. It accepts a pair of electron to become a Lewis Acid

Answer:

Interesting question, and the answer is yes, a substance can be a Lewis acid but not a Bronsted-Lowrey acid. To see this, let’s take a look at the definitions of each.

Explanation:

Bronsted-Lowrey acid:

A compound that is a hydrogen ion (proton) donor. When dissolved in the solvent in question, these compounds lose a proton to the solution. The concentration of these protons in solution is referred to as acidity, and is measured on the pH scale.

Lewis acid:

A substance that is an electron pair receiver. In solution, free electron pairs will form bonds with the substance, either ionic or covalent. In this definition, a proton is itself an acid, rather than a part of an acid.

A key thing to note here is that, in the Bronsted-Lowrey definition, there must be a proton. That means, all Bronsted-Lowrey acids are of the form  HXn→H++Xn− , showing the dissociation in solution. However, a Lewis acid needs only to have the ability to accept an electron pair, which means that  H+  is a Lewis acid, instead of what makes a compound an acid. Additionally, that means that the number of compounds that qualify as a Lewis acid are expanded. A favorite example of mine is boron trifluoride, or  BF3 . It is a common reagent in organic synthesis, it is a Lewis acid, but does not have any hydrogen, so it cannot be a Bronsted-Lowrey acid

Answer:

2H + O -------> H2O

and hydrogen react with oxygen so it is oxide of hydrogen

like iron react with Oxygen and give

iron oxide

Explanation:

after passing electric current in the water the two gases will get seperated and on bringing the matchstick close to hydrogen it will burn with a pop sound

Answer:

The correct option is;

d. Explicit knowledge

Explanation:

Explicit knowledge is the knowledge that can be easily articulated documented stored in a retrieval system accesses, transmitted and shared with others

Tacit knowledge is the skill developed by an individual based on actual experience such that such knowledge comprise of both facts and perspectives

Hence explicit knowledge and tacit knowledge are complementary

The operations performed by Kaia include documentation, storing in a retrieval system (her project report) and accessing what she documented, this is an example of explicit knowledge.

Answer: 1.29 moles of ethylene glycol must be added to 1 kg of water to make a solution with a freezing point of -2.4°C. Molality of solution is 1.29 m.

Explanation:

Depression in freezing point is given by:

[tex]\Delta T_f=i\times K_f\times m[/tex]

[tex]\Delta T_f=T_f^0-T_f=(0-(-2.4))^0C=2.4^0C[/tex] = Depression in freezing point

i= vant hoff factor (for non electrolyte , i = 1)

[tex]K_f[/tex] = freezing point constant for water= [tex]1.86^0C/kgmol[/tex]

m= molality =[tex]\frac{\text{moles of solute}}{\text{weight of solvent in kg}}[/tex]

m= molality =[tex]\frac{x}{1kg}[/tex]

[tex]2.4^0C=1\times 1.86^0C/kgmol\times \frac{x}{1kg}[/tex]

[tex]x=1.29[/tex]

Molality = [tex]\frac{\text{moles of solute}}{\text {weight of solvent in kg}}=\frac{1.29mol}{1kg}=1.29m[/tex]

Thus 1.29 moles of ethylene glycol must be added to 1 kg of water to make a solution with a freezing point of -2.4°C. Molality of solution is 1.29 m.

Answer:

1) C (m=T f/Kf)

2) 2.4 C

3) 1.3 m

4) 1.3 moles

Explanation:

This is correct on ed

Answer:

C. The electron clouds are negatively charged and repel each other as far apart as possible

Explanation:

This is the basis of VSEPR theory.

The angles between the electron clouds determine the shapes of the molecules.

B. and D. are wrong. All electron pairs are negatively charged.

The electrons affect the structure of a molecule because the bonding pairs are positively charged and lone pairs are negatively charged and they push each other into certain shapes.

Every atom or molecule consist some kind of geometry or shapes like linier, tetrahedral, square planner, octahedral etc. with some bond length and angles present with them.

The bond pairs in a geometry is made up with positive charge and lone pairs present on the atom in the form of negative charge as they both are opposite in nature and repel or push each other in opposite direction.

Due to this phenomena the structure of the atom gets effected and geometry will change on the basis of lone pair and bond pair repulsion.

Therefore, electrons affect the structure of a molecule because the bonding pairs are positively charged and lone pairs are negatively charged and they push each other into certain shapes.

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