Question

Two tanks A and B contain water at 30°C and
80°C respectively. The amount of water that
must be taken from A and B to prepare 40 kg
water at 50°C.
(1) 24 kg, 16 kg (2) 16 kg, 24 kg
(3) 20 kg, 20 kg (4) 30 kg, 10 kg​

Answer 1

i think ans- 4 hoga.....

Answer 2

The amount of water that must be taken from A and B to prepare 40kg water at 50°C is 24kg, 16kg (1).

Let the mass of water taken from tank A be x kg.

Then, the mass of water taken from tank B = 40-x kg.

We know, H=mst,

where m=mass of water, s = specific heat of water and t=temperature change.

• Heat absorbed by tank A= xs(50-30) J

• Heat released by tank B=(40-x)s(80-50) J

Now,

$H_{A}=H_{B}$

⇒$xs(50-30)=(40-x)s(80-50)$

⇒$20x=30(40-x)$

⇒$2x=120-3x$

⇒$x=24$

• Mass of water taken from tank A = 24kg

• Mass of water taken from tank B = (40-24) kg = 16kg.