%Mass
Ar C = 12 g/mol, Mr C₄H₁₀ = 58 g/mol, Ar H = 1 g/mol

or

Answer:
4 × 10 g
Explanation:
Step 1: Write the balanced equation
2 H₂(g) + O₂(g) ⇒ 2 H₂O(I)
Step 2: Calculate the moles corresponding to 4 g of H₂
The molar mass of H₂ is 2.02 g/mol.
4 g × 1 mol/2.02 g = 2 mol
Step 3: Calculate the moles of H₂O produced from 2 moles of H₂
The molar ratio of H₂ to H₂O is 2:2. The moles of H₂O produced are 2/2 × 2 mol = 2 mol.
Step 4: Calculate the mass corresponding to 2 moles of H₂O
The molar mass of H₂O is 18.02 g/mol.
2 mol × 18.02 g/mol = 4 × 10 g
Endothermic or C, if you would like a reason why, do not hestitate to ask
Answer:
The pressure increases by a factor of four.
Explanation:
Let's consider a gas at a given temperature and pressure (T₁, P₁). The absolute temperature of a gas is increased four times (T₂ = 4 T₁) while maintaining a constant volume. We can assess the effect on the pressure (P₂) by using Gay Lussac's law.
P₁/T₁ = P₂/T₂
P₂ = P₁ × T₂/T₁
P₂ = P₁ × 4 T₁/T₁
P₂ = 4 P₁
The pressure increases by a factor of four.