Answer:
+3
Explanation:
Chlorine is anion with a -1 charge. But they are three chlorine atoms.
-1 * 3 = -3
So they have a -3 charge.
So to balance the compound, the nickel has to be a cation with a +3 charge.
-3 + 3 = 0
Furthermore, a chemical bond always has a 0 charge. Remember that.
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Answer: Number of molecules of hydrogen gas 
Explanation:

Number of moles of sodium =
According to reaction , 2 moles of sodium produces 1 mole of hydrogen gas , then 2.11 mol of sodium will=
of hydrogen gas that is 1.05 moles of hydrogen gas.
Number of molecules =
moles of substance
Moles of hydrogen gas formed = 1.05 moles
Number of molecules of hydrogen gas =
moles of hydrogen gas
Number of molecules of hydrogen gas 
<u>Answer:</u> The Henry's law constant for oxygen gas in water is 
<u>Explanation:</u>
To calculate the molar solubility, we use the equation given by Henry's law, which is:

where,
= Henry's constant = ?
= solubility of oxygen gas = 
= partial pressure of oxygen gas = 2.1 atm
Putting values in above equation, we get:

Hence, the Henry's law constant for oxygen gas in water is 
Answer:
3.91 moles of Neon
Explanation:
According to Avogadro's Law, same volume of any gas at standard temperature (273.15 K or O °C) and pressure (1 atm) will occupy same volume. And one mole of any Ideal gas occupies 22.4 dm³ (1 dm³ = 1 L).
Data Given:
n = moles = <u>???</u>
V = Volume = 87.6 L
Solution:
As 22.4 L volume is occupied by one mole of gas then the 16.8 L of this gas will contain....
= ( 1 mole × 87.6 L) ÷ 22.4 L
= 3.91 moles
<h3>2nd Method:</h3>
Assuming that the gas is acting ideally, hence, applying ideal gas equation.
P V = n R T ∴ R = 0.08205 L⋅atm⋅K⁻¹⋅mol⁻¹
Solving for n,
n = P V / R T
Putting values,
n = (1 atm × 87.6 L)/(0.08205 L⋅atm⋅K⁻¹⋅mol⁻¹ × 273.15K)
n = 3.91 moles
Result:
87.6 L of Neon gas will contain 3.91 moles at standard temperature and pressure.