Order the liquids from most dense to least dense: Water, Pancake Syrup/Maple Syrup, Cooking Oil, Milk, Dish Soap

Use this information to determine the number of valence electrons in the atoms. Which of the following correctly compares the st

vlabodo [156]

The question is incomplete. The complete question is :

The table compares the number of electrons in two unknown neutral atoms.

Comparison of Electrons

Atom Number of Electrons

A 9

D 11

Use this information to determine the number of valence electrons in the atoms. Which of the following correctly compares the stability of the two atoms?

A. Both are unreactive.

B. Both are highly reactive.

C. A is unreactive and D is reactive.

D. A is reactive and D is unreactive.

Answer:

B. Both are highly reactive.

Explanation:

Atomic number of electrons given is 9 and 11, it means that atom A is fluorine (F) and atom D is Sodium (Na).

In order to gain stability 8 electrons are required in outer shell. So atoms either gain or lose electrons in its outer shell to become more reactive.

Sodium has electronic configuration (2,8,1) and easily loses one electron and become (2, 8) which is highly reactive.

Fluorine has electronic configuration (2, 7) and can gain easily an electron and becomes reactive to form (2, 8).

So, both they both attain stability by losing and gaining only one electron.

Hence, they both are highly reactive and the correct option is B.

8 0

3 years ago

A 0.450 g sample of solid lead(II) nitrate is added to 250 mL of 0.250 M sodium iodide solution. Assume no change in volume of t

Verdich [7]

Pb(NO₃)₂ ⇒limiting reactant

moles PbI₂ = 1.36 x 10⁻³

% yield = 87.72%

<h3>Further explanation</h3>

Given

Reaction(unbalanced)

Pb(NO₃)₂(s) + NaI(aq) → PbI₂(s) + NaNO₃(aq)

Required

moles of PbI₂
Limiting reactant
% yield

Solution

Balanced equation :

Pb(NO₃)₂(s) + 2NaI(aq) → PbI₂(s) + 2NaNO₃(aq)

mol Pb(NO₃)₂ :

= 0.45 : 331 g/mol

= 1.36 x 10⁻³

mol NaI :

= 250 ml x 0.25 M

= 0.0625

Limiting reactant (mol : coefficient)

Pb(NO₃)₂ : 1.36 x 10⁻³ : 1 = 1.36 x 10⁻³

NaI : 0.0625 : 2 = 0.03125

Pb(NO₃)₂ ⇒limiting reactant(smaller ratio)

moles PbI₂ = moles Pb(NO₃)₂ = 1.36 x 10⁻³(mol ratio 1 : 1)

Mass of PbI₂ :

= mol x MW

= 1.36 x 10⁻³ x 461,01 g/mol

= 0.627 g

% yield = 0.55/0.627 x 100% = 87.72%

7 0

3 years ago

Too much ___________ can slow and eventually stop the heart, and supplements should be taken only under the care of a physician.

Marina86 [1]

<span>Too much B. potassium can slow and eventually stop the heart, and supplements should be taken only under the care of a physician. </span>

6 0

3 years ago

Select all that apply.

wariber [46]

Answer:

The reaction is endothermic

Explanation:

we know that the reactants had to get energy from its surroundings which means that the reaction is endothermic

7 0

3 years ago

Josh is doing an experiment with water. He starts with a plastic cup of water that has a mass of 12 grams. He places the cup in

ra1l [238]

Answer: A) The mass of the cup of frozen water is 12 grams which means the mass did not change

Explanation:

The mass of water did not change, because the amount of matter is the same: by the law of mass conservation you can assure that the mass of water (12 grams) is the same at the begining than the end.

Both in the physical changes (as in the case of the changes in the phases of the matter) and in the chemical changes, the law of conservation of the mass is obeyed. Therefore, assuming that the liquid water did not spill from the sealed container during the night, the mass remained constant (12 grams).

Regarding the fact that Josh noticed the cup had cracked on its sides, you must observe that water is an exception to the common behavior of the matter: most substances shrink when pass from liquid state to solid state due to the fact that the particles (atoms, molecules or ions) lose kinetic energy and they the approach each other occupying less space.

Being the density inversely relatated to the volume (density = mass / volume), this increase on volume means that the substances will increase its density when pass from liquid to solid.

But water is a remarkable exception. Water density reaches its maximum at about 4°C, which means that solid water (0°C) is less dense than liquid water.

Hence, ice (solid water) will ocuppy more space (more volume) than the same amount of liquid water, which is the reason why the liquid water in the plastic cup expanded when it froze, cracking the cup.

4 0

3 years ago

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