Determine whether Z is a “poison”. Explain your reasoning.

Answer:

B. A gnat completes its life cycle in about 1 month.

Explanation:

Stage Time in Stage

egg 24 hours

larva 7 days

pupa 6 days

adult 2 weeks

Which of the following is a valid conclusion that Ivana can draw from her data?

A. Agnat generally does not live for more than 1 week.

B. Agnat completes its life cycle in about 1 month.

C. Agnat life cycle has more than five stages.

D. Agnat is a crustacean, not an insect.

Best describes the forces in the nucleus of a stable atom is the strong nuclear force balances out the electrostatic force.

The center region of an atom, which is composed of two different types of particles, is known as the atomic nucleus. Protons with positive charges and neutrons with no charges are present. Because of the strong electrostatic attraction between positively charged protons, atomic nuclei should be unstable, however they occasionally remain stable for more than a billion years.

The stability of nuclei suggests that protons and neutrons are attracted to one another by an attractive force. The strong nuclear force, also known as the residual strong force, is responsible for every individual atomic nucleus' stability. Neutrons and protons are held together by this basic force of nature. It is used to explain the atom's and its nucleus' stability, which is otherwise puzzling. It can be used to explain the origin of all atoms and, consequently, the origin of all known simple and complex molecules.

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Answer:

2 significant figures

Good luck with your work! :)

Answer:

False

Explanation:

While we do know that A. Leeuwenhoek used a simple microscope that consisted of only 1 lens, Hooke used a compound microscope. Although, after trying a compound microscope, Hooke found out that it strained his eyes and continued to use a simple microscope for his Micrographia.

Thus, we can say that the (compound) microscopes used today are different than the (simple) microscope used by Hooke and Leeuwenhoek.

Answer:

A. The mass of reactants is the same as the mass of products

Answer:

We should manage and conserve forest resources in Nepal.

Explanation:

Nepal is the second richest country in natural resources. We should all work together and conserve our natural resources. We can conserve and manage forests in Nepal by the following ways:

1. Proper rules and laws should be made as well as executed by our government.

2. Illegal activities regarding harm of forests and its resources should be totally band.

3. Awareness programmes should be conducted worldwide to aware our citizens regarding conservation of forests.

From the stoichiometry of the balanced reaction equation, the correct statement are;

The term combustion refers to the burning of fossil fuels for the purpose of energy production. The equation for reaction is CH4 + 2O2 ---> CO2 + 2H2O.

Using this equation as shown, the true statements are;

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Answer:

To keep apparatus, chemicals and carry out experiments

Using the stoichiometry of the reaction and the information provided in the question, the mass of N2 used is 11.62 g.

The term chemical reaction refers to the combiantion of two or substances to yiled one or more products. The reaction equation in this case is N2 + O2 --->2NO.

Now;

Number of moles of NO = 25g/30 g/mol = 0.83 moles

1 mole of N2 yields 2 moles of NO

x moles of N2 yileds 0.83 moles of NO

x = 0.415 moles

Mass of N2 = 0.415 moles * 28 g/mol = 11.62 g

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Answer:

1.  Place in a platic bag and use a magnet to attract the iron filings.  [See explanation for an alternative step].

2. Disolve the remainer in water

3.  Pass the liquid through a microporous filter to capture the undissolved sulfur

4.  Evaporate the filtered water to retrieve iron chloride crystals

Explanation:

The Fe(II) chloride will dissolve in water.  It is paramagnetic, and thus is weakly attracted to a magnet.  The process above should not result in attracting the solid Fe(II) crystals.  In fact, it is probably acceptable to dissolve the entire sample in water as the fisrt step.  The dissolved Fe(II) chloride should also not be strongly attraced to a magnet, and htis step would allow easier separation of the iron filings.

Sulfur is not soluble in water, so it will collect as a dsolid in the microporous filter.

The Fe(II) has a high solubility, so it will wind up in the filtered soluition.  Evaopate using heat or vacuum to retrieve the solid Fe(II) chloride crystals (they will be hydrated).

Answer:

the basic elements of environment are lithosphere, hydrosphere, atmosphere and biosphere.

Explanation:

[tex]\qquad\qquad\huge\underline{{\sf Answer}}♨[/tex]

Here's the balanced chemical equation for above reaction ~

[tex]\qquad \sf  \:LiBr + F \rightarrow Li F + Br[/tex]

Here, fluorine is more more more reactive than Bromine, therefore it replaces Bromine from its compound and forms Lithium floride.

n this questions certain

a

r

e

g

i

v

e

n

,

of moles ,n = 21 mol, Pressure P = 78 atm, Temperature T = 900 K, Volume V = ?

We have to calculate the volume of the given moles of gas at specific temperature and pressure.

Using Ideal Gas equation;

PV = nRT

V = nRT /P ( R = gas constant = 0.08206 L atm

m

o

l

−

1

K

−

1

)

V= 21 mol x 0.08206 L atm

m

o

l

−

1

K

−

1

x 900K / 78 atm

V= 73.854 L atm / 78 atm = 0.946 L

Answer:

 A chemical reaction can release chemical energy stored in batteries, natural gas, and even coal. The main advantage of chemical energy is that it is abundant in nature. Chemical energy can be produced by many organic materials.

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Mark Brainleast!!!!!!!!!!!!

a. the mole of substance

b.a standard solution

in analytical chemistry standard solution is a solution containing a precisely known concentration of an element or a substance.

A known mass of solute is dissolved to make a specific volume. it is prepared using a standard solution,such as a primary standard.

hope this helps you

Answer:

the dendritic cell consumes the pathogen by phagocytosis

Answer:

the correct answer false

Explanation:

Answer:

"The Roman numeral denotes the charge and the oxidation state of the transition metal ion. For example, iron can form two common ions, Fe2+ and Fe3+. To distinguish the difference, Fe2+ would be named iron (II) and Fe3+ would be named iron (III)."

Explanation:

In chemistry, Roman numerals are used for a specific group of elements called transition metals. The Roman numerals indicate the charges that these metals carry in a compound.

Sodium hydroxide is a soluble strong base. The pOH of a 3.0 × 10⁻³ M-sodium hydroxide solution is 2.5.

According to Arrhenius, a base is a species that releases OH⁻ ions in an aqueous medium.

Let's consider the basic reaction of NaOH.

NaOH(s) ⇒ Na⁺(aq) + OH⁻(aq)

NaOH is a strong base. This means that the concentration of OH⁻ will be equal to the initial concentration of NaOH, i.e. 3.0 × 10⁻³ M.

Then, we can calculate the pOH of the NaOH solution using the following expression.

pOH = -log [OH⁻] = -log 3.0 × 10⁻³ = 2.5

Sodium hydroxide is a soluble strong base. The pOH of a 3.0 × 10⁻³ M-sodium hydroxide solution is 2.5.

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Answer:2.5

Explanation:

Answer:

4:6    and  4:4

Explanation:

double the right side so double the left side to get these ratios

Answer:

Except for mature red blood cells, all human cells contain a complete genome. DNA in the human genome is arranged into 24 distinct chromosomes—physically separate molecules that range in length from about 50 mil- lion to 250 million base pairs.

Answer:

As represented by this huge stack of paper, the human genome contains more than three billion nucleotides or DNA "letters.".

Explanation:

.

Answer:

2 mol/L

Explanation:

molarity = moles/litres

NaOH = 23 + 16 + 1 = 40 g/mol

[tex] ? \: mol \: naoh \: = 8 \: g \: naoh \: \times \\ \frac{1 \: mol \: naoh}{40 \: g \: naoh} = 0.2 \: mol \: naoh[/tex]

molarity = 0.2 mol/0.1 L = 2 mol/L

Answer:

9.69g

Explanation:

Xmol of n2= 7.774/22.4= 0.346 mole

molar mass of n2 2×14 =28g/Mol

Mas of n2= 0.346×28

Mas of n2=9.69grams

Answer:

10.25

Explanation:

There I proved it

Answer:

pOH = 12.10

Explanation:

pOH = 14 - pH = 14 - 1.90 = 12.10

Explanation:

Haloalkanes and other compounds with the halogen atom bonded to either sp3-hybridized or sp2-hybridized carbon atoms (aryl and vinyl halides) react with magnesium metal to yield organomagnesium halides called Grignard reagents. Grignard reagents are usually prepared in diethyl ether (CH3CH2O─CH2CH3). An ether solvent is essential for the reaction. The French chemist Victor Grignard discovered this reaction in 1900, and it has been studied and used extensively ever since.

Grignard reagents form easily from 1°, 2°, and 3° alkyl halides, although their reactivities differ. Aryl and vinyl halides react somewhat more slowly, and the cyclic ether tetrahydrofuran (THF) is required to prepare Grignard reagents of these compounds. The higher boiling point of the cyclic ether provides more vigorous reaction conditions, but the rate of the reaction also increases because THF solvates the Grignard reagent better than diethyl ether.

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Molecular model of a complex of methyl-magnesium chloride, a Grignard reagent, in which two molecules of tetrahydrofuran, THF, are bound to magnesium. The model is based on the crystal structure.

The order of reactivity of the halogens in haloalkanes is I > Br > CI > > F. Organofluorides are so unreactive that they are never used to prepare Grignard reagents. Organohalogen compounds containing bromine and chlorine are readily available, and are commonly used to prepare Grignard reagents. Grignard reagents are used synthetically to form new carbon–carbon bonds. A Grignard reagent has a very polar carbon–magnesium bond in which the carbon atom has a partial negative charge and the metal a partial positive charge.

The polarity of the carbon–magnesium bond is opposite that of the carbon–halogen bond of haloalkanes. Because the carbon atom in a Grignard reagent has a partial negative charge, it resembles a carbanion, and it reacts with electrophilic centers such as the carbonyl carbon atom of aldehydes, ketones, and esters. We will discuss this chemistry extensively in later chapters.

Grignard reagents react rapidly with acidic hydrogen atoms in molecules such as alcohols and water. When a Grignard reagent reacts with water, a proton replaces the halogen, and the product is an alkane. The Grignard reagent therefore provides a pathway for converting a haloalkane to an alkane in two steps.

For a Forty miles above the earth's surface, the temperature at 250k and the pressure at only 0.20 torr, the density of air at this altitude  is mathematically given as

d=3.732*10{-4}g/l

Generally, the equation for the ideal gas   is mathematically given as

PV=(m/mw)RT

Therefore

d=m/v

d=26,664*20/83.14*250

d=0.37152

d=3.732*10{-4}g/l

In conclusion, the density

d=3.732*10{-4}g/l

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