Answer:
c. 8.1 L
Explanation:
Given that:-
Moles of oxygen gas = 0.50 mol
According to the reaction shown below as:-

3 moles of oxygen gas on reaction gives 2 moles of ozone
Also,
1 mole of oxygen gas on reaction gives 2/3 moles of ozone
So,
0.50 mole of oxygen gas on reaction gives
moles of ozone
Moles of ozone = 0.3333 mol
Pressure = 1 atm
Temperature = 25.0 °C
The conversion of T( °C) to T(K) is shown below:
T(K) = T( °C) + 273.15
So,
T = (25.0 + 273.15) K = 298.15 K
Volume = ?
Using ideal gas equation as:
PV=nRT
where,
P is the pressure
V is the volume
n is the number of moles
T is the temperature
R is Gas constant having value = 0.0821 L.atm/K.mol
Applying the equation as:
1 atm × V = 0.3333 mol × 0.0821 L.atm/K.mol × 298.15 K
⇒V = 8.1 L
Answer: 2. cannot be an element.
Explanation:
Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Copper 
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: methane 

Thus as it can be decomposed into its constituent elements, it is a compound.
Mixture is a substance which has two or more components which do not combine chemically and do not have any fixed ratio in which they are present.
Thus methane cannot be an element.
Answer:
Equal volumes of SO2(g) and O2(g) at STP contain the same number of molecules
Explanation:
According to Avogadro Law,
Equal volume of all the gases at same temperature and pressure have equal number of molecules.
This law state that volume and number of moles of gas have direct relation.
When the amount of gas increases its volume will increase and when the amount of gas decreases its volume will decrease.
Mathematical relation:
V ∝ n
V/n = K
K is proportionality constant.
When number of moles change from n₁ to n₂ and volume from V₁ to V₂
expression will be,
V₁/n₁ = K , V₂/n₂ = K
V₁/n₁ = V₂/n₂
Thermoplastic and thermosetting
thermoplastic:- they are easily molded and extruded into films, fibres and packaging.For eg. PVC
thermosetting:-they are hard and durable and can be used for aircraft parts,tires and auto parts .For eg. phenolic resins.
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