Section – B If the formula of Borax is Na2B4O7.(OH)2, then x + y… — Solution | JEE Chemistry

NVAEasyJEE 2023Mole Concept

Section – B

If the formula of Borax is Na $_2$ B $_4$ O $_7$ .(OH) $_2$ , then $x + y + z$ = ?

The formula of borax is Na $_2$ B $_4$ O $_7$ .(OH) $_2$

Answer

Correct answer:17

Standard Method

Given: The formula of borax is Na $_2$ B $_4$ O $_7$ .(OH) $_2$ .

Find: The value of $x + y + z$ .

From the formula, we count:

So,

2 + 4 + 7 + 2 = 17

Therefore, $x + y + z = 17$ .

Counting only Na, B, and O atoms but ignoring the $(OH)_2$ part. This is wrong because the hydroxyl groups are explicitly present in the formula. Include every term written in the formula.
Misreading subscripts as coefficients. This is wrong because subscripts show how many atoms or groups are present within one formula unit. Read $Na_2$ , $B_4$ , $O_7$ , and $(OH)_2$ carefully.

Get unlimited AI-adaptive practice, mastery tracking, and an AI tutor that explains every step — free to start.