okay this is kinda easy
<u>What is the gravitational field strength on the moon?</u>
The Moon has a gravitational field strength of 1.6 N/kg.
<h3>Option B</h3><h3>The time constant of a 10 H inductor and a 200 ohm resistor connected in series is 50 millisecond</h3>
<em><u>Solution:</u></em>
Given that,
10 H inductor and a 200 ohm resistor connected in series
To find: time constant
<em><u>The time constant in seconds is given as:</u></em>

Where,
L is the inductance in henry and R is the resistance in ohms

Convert to millisecond
1 second = 1000 millisecond
0.05 second = 0.05 x 1000 = 50 millisecond
Thus time constant is 50 millisecond
Letters A and D appear to be correct.
Explanation:
velocity = 15 km/hr = 15×1000m / 60×60s
= 4.17 m/s
time= 20 min= 20 × 60s
= 1200s
displacement =?
we know that,
V = D / t
or, 4.17 = D / 1200
or, D = 4.17 × 1200
or,D = 5004 m
Density is the mass per unit volume of a substance and is simply the ratio of mass to volume. Unlike mass, density is a characteristic property of a material, meaning a property that has the same value for any size sample of a given substance.
Hope this helps:)