B) ionic bond
(although in reality, every bond is fundamentally the sharing of a pair of electron. but due to unmutal electonegativity, the molecule becomes polar)
Boyle's law of ideal gas: This law states that the volume of a gas is inversely proportional to its pressure at a constant temperature. Acc to this law we can write the relation of pressure and volume as:

That means:

From that equation we can calculate Volume of gas at a certain pressure:
P₁=Initial pressure
V₁=Initial volume
P₂=Final pressure
V₂= Final volume
Here P₁, initial pressure is given as 85.0 kPa
V₁, initial volume is given as 525 mL
P₂, final pressure is 65.0 kPa

so,
V_{2}=85\times 525\div 65
=686 mL
Volume of gas will be 686 mL.
Answer:
No, gases move freely all over the place, liquids move more freely but in a more contained area, and solids the molecules are rigid, at the most the movement is small vibration as the molecules put pressure on one another to hold their form and stay in place.
The volume of O₂ : 21 L
<h3>Further explanation</h3>
Given
8.7 grams of C₂H₄
Required
Volume O₂
Solution
Reaction
C₂H₄ + 3 O₂ ⇒ 2 CO₂ + 2 H₂O
mol C₂H₄(MW= 28 g/mol) :
= mass : MW
= 8.7 g : 28 g/mol
= 0.311
From the equation, mol O₂ :
= 3/1 x mol C₂H₄
= 3/1 x 0.311
= 0.933
At STP, 1 mol gas=22.4 L, so for 0.933 mol :
= 0.933 x 22.4 L
= 20.899 L ≈ 21 L
Since the two atoms have the same number of protons they are the same element. The fact that they have different numbers of neutrons makes them isotopes. The best answer is A.