Answer:
Step-by-step explanation:
Time period, T = 4.2 s
The time period of a body in SHM with a spring is given by

where, m is the mass of the body and k be the spring constant.
(a) As the time period of the body is directly proportional to the square root of the mass of the body, so if the mass is doubled, the time period becomes √2 times the original time period.
So, T' = √2 T
T' = 1.414 x 4.2 = 5.9 second
(b) If mass is halved, the new time period becomes 1/√2 times the original time period.
T' = 4.2 / 1.414 = 3 second
(c) Time period does not depend on the amplitude, so the time period remains same , i.e., 4.2 s.
(d) As the time period is inversely proportional to the square root of teh spring constant, so as the spring constant is doubled, time period becomes 1/√2 times the original time period.
T' = 4.2 / 1.414 = 3 second