Question

1. A lump of element X can be cut by a knife. During its reaction with water X floats and melts.at is X?A calciiumB copperC magnesiumD potassium​

Answer 1

Explanation:

the answer will be

D potassium

as potassium floats in water because it is less denser than water which makes it float and

also potassium has low melting pointwhich melts fast

Answer 2

A lump of element X can be cut by a knife. During its reaction with water X floats and melts then X is potassium.

Explanation:

We know that density of potassium is less than the density of water. Whereas density of calcium, copper and magnesium is greater than the density of water.

Therefore, these elements when placed in water then they sink. Also, potassium is a soft metal which can be easily cut with the help of a knife. When potassium is added to water then an exothermic reaction occurs due to which it melts in water.

Learn more about soft metals:

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