Solved: CHEMISTRY Question for NEET

NEET CHEMISTRYMedium

Identify the correct statements from the following: (a) $CO_2(g)$ is used as a refrigerant for ice cream and frozen food. (b) The structure of $C_{60}$ contains twelve six-carbon rings and twenty-five five-carbon rings. (c) ZSM-5, a type of zeolite, is used to convert alcohols into gasoline. (d) CO is a colorless and odorless gas.

(a) and (c) only

(b) and (c) only

(a), (c) and (d) only

Step-by-Step Solution

Statement (a) is Incorrect: Solid $CO_2$ (known as Dry Ice), not gaseous $CO_2$ , is used as a refrigerant for ice cream and frozen food because it sublimes directly to gas at –78°C, providing cooling without leaving liquid residue [Source 105 mentions sublimation of dry ice].
Statement (b) is Incorrect: Buckminsterfullerene ( $C_{60}$ ) has a shape like a soccer ball. It contains 20 six-membered rings (hexagons) and 12 five-membered rings (pentagons), not the numbers stated in the option.
Statement (c) is Correct: ZSM-5 is a shape-selective zeolite catalyst with a pore structure that allows it to convert alcohols (like methanol) directly into gasoline (a mixture of hydrocarbons) by dehydration.
Statement (d) is Correct: Carbon monoxide (CO) is a colorless, odorless, and almost water-insoluble gas. Its odorless nature makes it particularly dangerous as a pollutant [Source 123 discusses CO toxicity].

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