Question

A metal from period IV is added to water and a vigorous reaction takes place with the evolution of a gas. Which statements are correct?
1.Oxygen is evolved
2.Hydrogen is evolved
3.The resulting solution is acidic
4.The resulting solution is basic
A. 1 and 3 only
B. 2 and 3 only
C. 2 and 4 only
D. 1 and 4 only

Answer 1

n this question, we have to find a metal from period 4 and after that add this metal to the water. You will observe that this reaction takes place very fast with the evolution of gas. So we have to check from the given statement which one is correct. By using the concept of metals and non metals we will solve this given question.

Complete step by step answer:
Firstly we have to see the elements of period ${\text{IV}}$ which are K, Ca, Ga, Ge etc.
So as we have to choose which statement is correct or which gas is evolved. Let us consider an example, so here if we take Ca the reaction with water would be given below:
${\text{Ca + }}{{\text{H}}_{\text{2}}}{\text{O}} \to {\text{Ca}}{\left( {{\text{OH}}} \right)_{\text{2}}}{\text{ + }}{{\text{H}}_{\text{2}}}$
Hope by this reaction you will clear that both basic that is ${\text{Ca}}{\left( {{\text{OH}}} \right)_{\text{2}}}$and ${{\text{H}}_{\text{2}}}$is evolved.
There are some elements which react very violently with the water, so these are some water – sensitive chemicals. There are some alkali metals also which react with water to produce heat and hydrogen gas which can combine explosively with atmospheric oxygen that alkali metals are like sodium, potassium and lithium.

So, the correct answer is “Option A”.

Additional Information:
Almost when a metal reacts with the water so hydrogen gas is produced. So let us take an example and you will understand more. Here we take a metal that is sodium. When sodium metal reacts with water, immediately the resulting heat melts the metal into a grey – silver ball. During this reaction hydrogen gas is evolved and the ball rapidly propels across the surface of water, leaving a white trail of sodium hydroxide after that which eventually dissolves into a clear solution.

Note:
Now this is a very effective way for you to remember the names of elements. Five out of six alkali metals which react with air and water also. They are Lithium (Li) , Sodium (Na) , Potassium (k) , Rubidium (Rb) , Caesium (Cs) .