JEE Main Test 21

Result

JEE Main Test 21

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Weekly Quiz Competition

Question 1
4 / -1

In a compound, atoms of element Y from ccp lattice and those of element X occupy 2/3^rd of tetrahedral voids. The formula of the compound will be

A
X₂Y

B
X₃Y₄

C
X₄Y₃

D
X₂Y₃

Solution

Effective no. of atoms of Y = 4
No. of Td voids = 8
No. of X-atoms =(2*8)/3 = 16/3
So, ratio of X:Y is 16/3 : 4 or 4/3 : 1 or 4:3
Hence the formula is X₄Y₃
Question 2
4 / -1

Experimentally it was found that a metal oxide has formula M_0.98O. Metal M, is present as M²⁺ and M³⁺ in its oxide. Fraction of the metal which exists as M³⁺would be

A
4.08%

B
6.05%

C
5.08%

D
7.01%

Solution

Metal oxide = M_0.98O
If ‘x’ ions of M are in +3 state, then
3x + (0.98 – x) × 2 = 2
x = 0.04
So the percentage of metal in +3 state would be 0.04/.98 x 100 = 4.08%
Hence, option A is correct.