Answer:

Explanation:
Ba(OH)₂ + 2HCl ⟶ BaCl₂ + H₂O
V/mL: 249
c/mol·L⁻¹: 0.0443 0.285
1. Calculate the moles of Ba(OH)₂

2. Calculate the moles of HCl
The molar ratio is 2 mol HCl:1 mol Ba(OH)₂

3. Calculate the volume of HCl

The volume is 19.76987448 by taking the known variables mass=18.9g and density=0.956g/ml
To get volume you divide the mass by the density which gives you about
19.77 ml in volume
Answer : The mass of
occupy 30.3 L under the same conditions will be, 24.9 grams.
Explanation :
First we have to calculate the moles of 

Now we have to calculate the moles of
in 30.3 L by using Avogadro's law.
Avogadro's law : It is defined as the volume of gas is directly proportional to the number of moles of gas at constant pressure and temperature.

or,

where,
= initial volume of gas = 6.21 L
= final volume of gas = 30.3 L
= initial moles of gas = 0.16 mol
= final temperature of gas = ?
Now put all the given values in the above equation, we get:


Now we have to calculate the mass of 

Molar mass of
= 32 g/mol

Therefore, the mass of
occupy 30.3 L under the same conditions will be, 24.9 grams.