Which among the following is the strongest acid ?

A system does 200 J of work and at the same time absorbs 150 J of heat. The magnitude of the change in internal energy is ____________ J. (Nearest integer)

An accelerated electron has a speed of 5 $$\times$$ 10⁶ ms^$$-$$1 with an uncertainty of 0.02%. The uncertainty in finding its location while in motion is x $$\times$$ 10^$$-$$9 m. The value of x is ____________. (Nearest integer)

[Use mass of electron = 9.1 $$\times$$ 10^$$-$$31 kg, h =6.63 $$\times$$ 10^$$-$$34 Js, $$\pi$$ = 3.14]

Number of electrons present in 4f orbital of Ho³⁺ ion is ____________. (Given Atomic No. of Ho = 67)