(A) Time-period in spring-block system is given by, T=2πkm​​ If mass is doubled, T′=2πk2m​​ ⇒ T′=2​T Hence, time period becomes 2​ times, if the mass of the block is doubled. (A→4) (B) For spring, PE=21​kx2 If spring constant is increased 4 times, PE becomes 4 times. (B→3) (C) Speed of the block, v=ωA Hence, velocity of the block becomes twice when amplitude of the oscillation is doubled. (C→2) (D) Energy of the oscillation, E=21​mω2a2E′=21​mω′2a2⇒E′=21​m(2ω)2a2=24​mω2a2(∵)′=2ω) ⇒ E' = 4E Energy of the oscillation becomes 4 times when angular frequency is doubled. (D→1)