Moderate

Formalin is ___________ solution of formaldehyde in water?

Correct answer: C. 40%

  • A. 10%
  • B. 20%
  • C. 40%
  • D. 60%

Explanation

Formalin is conventionally a concentrated aqueous solution containing about 40% formaldehyde by mass, often stabilized with a small amount of methanol. The likely mistake is choosing 52%, which is the approximate water content of the complete commercial mixture, not the formaldehyde concentration.

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About Preparation of Aldehydes and Ketones

Aldehydes and ketones are prepared mainly by controlled oxidation or dehydrogenation of primary and secondary alcohols, respectively. The topic also includes ozonolysis of alkenes, hydration of alkynes and preparation through acyl derivatives, with attention to why primary alcohols can give aldehydes whereas secondary alcohols give ketones.

Practise Aldehydes and Ketones

679 free Aldehydes and Ketones MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.

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