Vinay Jaiswal
@Vinay Jaiswal
Best posts made by Vinay Jaiswal

RE: Neet
Go through previous year papers of neet, you will understand which problems to solve from hc verma
Latest posts made by Vinay Jaiswal

RE: Radioactivity
it is like, some other nuclei must be decay to form the required nuclei.
suppose we are talking about nuclei name B and it is formed by decay of nuclei A so it can be possible that the formation rate of B = decay rate of Bdecay rate is (decay constantno. of nuclei at time t) as No is nuclei no. at t=0 but at any other time it will be different and suppose it is N.
so now rate of decay = rate of formation
λN=a
N= a/λ 
RE: Shm
it is like case a. length is same but it is going upwards with some acceleration

RE: Oscillation
you can use x=Asin(wt+phi) and given condition is at t=0 x=A
you will get phi = pie/2 then the equation will be x=Acostwt 
RE: Atoms
@pranaysingh first, look at the basic concepts of p.e. and k.e.
the energy required to bring an electron from infinity to ground state is potential energy in ground state. it is ve for attractive force. It is assumed that the p.e. is 0 at infinity. so the p.e. in ground state = 27.2 eV as per the above mentioned assumption.
k.e. in ground state = +13.6 eV
so total energy = 13.6 eVNow, this question
it is not taking the above mentioned assumption that the p.e. is 0 at infinity.
total energy in 1st excited state = 23.8 eV
energy required for transition from n=1 to n=2 = 10.2 eV
total energy in ground state = 23.810.2 = 13.6 eV
k.e. in ground state = 13.6 eV
so p.e. in ground state = t.e.  k.e. = 0k.e. in ground state will always same as velocity will always be same.
energy required for transition from any state to other is fixed for each level.
p.e. depends on the assumption that at which point we are taking the 0 level p.e. 
RE: Atoms
in the above problem , it is assumed that the total energy is 23.8 eV but in reality it is not the case.

RE: Atoms
sorry, kinetic energy is always +ve . total energy in ground state = 13.6 eV
total energy = P.E. + K.E.
13.6 = P.E. + 13.6
p.e. = 0 
RE: Alcohol
in question, it is asked for chemically distinguishable so physical change is not required i.e. colour

RE: Radioactivity
it is given in the question to generalize it. penetrating power depends on particle type (alpha and beta) as they have different masses and energy when they emit while gamma rays has highest energy when it emits.