NEET · Chemistry · STD 11 - 1. Some basic concept of chemistry

When \(1 dm ^3\) of \(CO _2\) gas is passed over hot coke, the volume of gaseous mixture after complete reaction at STP becomes \(1.4 dm ^3\). The composition of the gaseous mixture at STP is :

A \(0.8 dm ^3\) of \(CO , 0.8 dm ^3\) of \(CO _2\)
B \(0.8 dm ^3\) of \(CO , 0.6 dm ^3\) of \(CO _2\)
C \(0.6 dm ^3\) of \(CO , 0.8 dm ^3\) of \(CO _2\)
D \(0.6 dm ^3\) of \(CO , 0.4 dm ^3\) of \(CO _2\)

Verified Solution

Answer & Solution

Correct Answer

(B) \(0.8 dm ^3\) of \(CO , 0.6 dm ^3\) of \(CO _2\)

Step-by-step Solution

Detailed explanation

(B) The reaction of carbon dioxide with hot coke is given by:
\(CO_2(g)+C(s) \rightarrow 2 CO(g)\)
Initial volume of \(CO _2=1 dm ^3\)
Let \(x dm ^3\) of \(CO _2\) react with hot coke.
Volume of \(CO _2\) remaining \(=1-x dm ^3\)
Volume of CO formed \(=2 x dm ^3\)
Total volume of the gaseous mixture \(=(1-x)+2 x=1+x dm ^3\)
Given that the total volume after the reaction is \((A)4 dm ^3\) :
\(1+x=(A)4\)
\(x=0.4 dm^3\)
Volume of \(CO _2\) remaining \(=1-0.4=0.6 dm ^3\)
Volume of CO formed \(=2 \times 0.4=0.8 dm ^3\)
The composition of the gaseous mixture is \(0.8 dm ^3\) of CO and \(0.6 dm ^3\) of \(CO _2\).

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

Same subject

Match the following aspects with the respective metal.

Aspects	Metal
\((a)\) The metal which reveals a maximum number of oxidation states	\((i)\) Scandium
\((b)\) The metal although placed in \(3 d\) block is considered not as a transition element	\((ii)\) Copper
\((c)\) The metal which does not exhibit variable oxidation states	\((iii)\) Manganese
\((d)\) The metal which in \(+1\) oxidation state in aqueous solution undergoes disproportionation	\((iv)\) Zinc

Select the correct option

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