# PHYSICS | Study Mode

Question 21
A
30cm
B
10cm
C
20cm
D
25m
##### Explanation
Clockwise moment = Anti-clockwise moment
10 x 30 = 15 x X
X = 20cm

Question 22
A
30s
B
20s
C
25s
D
15s
##### Explanation
t = $$\frac{u sin\theta}{g}$$ = $$\frac{300 \text {sin} 30}{10}$$ = 15s

Question 23
A
40s
B
10s
C
20s
D
5s
##### Explanation
t = $$\frac{v - u}{a}$$ = $$\frac{20 - 0}{2}$$

= 10s

Question 24
A
Visible Light
B
Ultraviolet rays
C
Infrared rays
D
Gamma rays

Question 25
A
5.93 x 106s
B
6.93 x 107s
C
6.93 x 109s
D
5.93 x 107s
##### Explanation
t1/2 = $$\frac{0.693}{\gamma}$$ = $$\frac{0.693}{10^-6}$$

= 6.93 x 107

Question 26
A
Water waves
B
C
Sound waves
D
X-rays

Question 27
A
201oC
B
126oC
C
153oC
D
185oC
##### Explanation
T = $$\frac{PV}{nR}$$ = $$\frac{7.6 x 10^6 x 10^-3}{6 x 8.3}$$

= 153oC

Question 28
A
Mass of water to the mass of an equal volume of liquid
B
Upthrust in the liquid to the upthrust in water
C
Density of water to the density of the liquid
D
Upthrust in water to the upthrust in the liquid
##### Explanation

Question 29
A
It will decrease
B
it will drop to zero
C
It will increase
D
It will remain constant
##### Explanation

Question 30
A
B
An electric bell
C
A moving coil galvanometer
D