Answer : The pressure of the helium gas is, 1269.2 mmHg
Explanation :
To calculate the pressure of the gas we are using ideal gas equation:

where,
P = Pressure of
gas = ?
V = Volume of
gas = 210. mL = 0.210 L (1 L = 1000 mL)
n = number of moles
= 0.0130 mole
R = Gas constant = 
T = Temperature of
gas = 
Putting values in above equation, we get:


Conversion used : (1 atm = 760 mmHg)
Thus, the pressure of the helium gas is, 1269.2 mmHg
Answer:
A. relative humidity B. air temperature C. air pressure D. atmospheric
Explanation:
2 NH3+ 2 O2 —> 2 NO+ 3 H2O
Explanation:
Anions and cations have different atomic sizes than the neutral atoms.
When the bromine atom becomes an anion, it ______ in size.
Anions involves gaining extra electrons. This basically leads to increased repulsion between the electrons and thereby increasing the size. Anions are always larger than the neutral atoms.
This means the answer is A. Increase
When the strontium atom becomes a cation, it ______ in size.
Cations involves losing valence electrons. This basically leads to a decrease in electron shells and electron repulsion thereby reducing the size. Cations are always larger than the neutral atoms.
This means the answer is B. Decrease