Explanation

In passive voice, the object (the piano) becomes the subject, and the verb form changes accordingly.

"Who" changes to "By whom," and the correct structure is "By whom was the piano stolen?"

Explanation

NaCl (sodium chloride) is a compound.

Because it consists of two different elements (sodium and chlorine) chemically bonded.

Explanation

Sand is primarily composed of silicon dioxide (SiO₂), formed when silicon and oxygen combine.

It is a common natural material found in deserts, beaches, and riverbeds.

Explanation

"Mine" is a possessive pronoun that shows ownership.

It replaces a noun phrase like "my car" to avoid repetition.

Explanation

Explanation

"Cut" is an irregular verb because its past tense and past participle forms are the same: cut – cut – cut.

Laugh, shout, paint are regular verbs that follow the pattern of adding -ed in past tense.

Explanation

Daily spending = 35 rupees, so for 7 days: 35 × 7 = 245 rupees.

Simple multiplication gives the total weekly expenditure.

Explanation

To subtract (-4) from (-6), change the subtraction to addition by changing the sign of the number being subtracted:

-6 - (-4) = -6 + 4

= -2

Explanation

The square root of 256 is 16, which has 2 digits.

Counting the digits in 16 confirms that the answer is 2.

Explanation

The infinitive phrase "to sleep" is modifying the noun "day", telling what kind of day.

Since it describes or qualifies a noun, it functions as an adjective.