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1

NEET 2016 Phase 2

MCQ (Single Correct Answer)
The number of electrons delivered at the cathode during electrolysis by a current of 1 ampere in 60 seconds is (charge on electron = 1.60 $$ \times $$ 10$$-$$19C)
A
6 $$ \times $$ 1023
B
6 $$ \times $$ 1020
C
3.75 $$ \times $$ 1020
D
7.48 $$ \times $$ 1023

Explanation

Q = I × t

Q = 1 × 60 = 60 C

Now, 1.60 × 10–19 C $$ \equiv $$ 1 electron

$$ \therefore $$ 60 C $$ \equiv $$ $${{60} \over {1.6 \times {{10}^{ - 19}}}}$$

= 3.75 $$ \times $$ 1020 electrons
2

NEET 2016 Phase 2

MCQ (Single Correct Answer)
Zinc can be coated on iron to produce galvanized iron but the reverse is not possible. It is because
A
zinc is lighter than iron
B
zinc has lower melting point than iron
C
zinc has lower negative electrode potential than iron
D
zinc has higher negative electrode potential than iron

Explanation

The reduction potential values are

Zn2+/Zn = – 0.76 V

Fe2+/Fe = – 0.44 V

Thus, due to higher negative electro potential value of zinc than iron, iron cannot be coated on zinc.
3

NEET 2016 Phase 2

MCQ (Single Correct Answer)
The molar conductivity of a 0.5 mol/dm3 solution of AgNO3 with electrolytic conductivity of 5.76 $$ \times $$ 10$$-$$3 S cm$$-$$1 at 298 K is
A
2.88 S cm2/mol
B
11.52 S cm2/mol
C
0.086 S cm2/mol
D
28.8 S cm2/mol

Explanation

$${\Lambda _m} = {{\kappa \times 1000} \over {Molality}}$$

= $${{5.76 \times {{10}^{ - 3}} \times 1000} \over {0.5}}$$

= 11.52 S cm2/mol
4

AIPMT 2015 Cancelled Paper

MCQ (Single Correct Answer)
A device that converts energy of combustion of fuels like hydrogen and methane, directly into electrical energy is known as
A
dynamo
B
Ni-Cd cell
C
fuel cell
D
electrolytic cell

Explanation

A device that converts energy of combustion of fuels, directly into electrical energy is known as fuel cell.

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