Physics, Chemistry, Mathematics Forums

In how man ways we can choose 3 squares on a chess board such that one of the squares has its two sides common to the other two squares?

what is the geometric interpretation of l z-(1+3i) l  + l z -( 1-3i) l = k , (a.) if k>6 (b.) if k=6 (c.) if k<6.

A sample of impure Magnesium is reacted with diluted Sulphuric Acid to give the respective salt and Hydrogen.If 1 gram of impure sample gave 298.6 cc of Hydrogen at STP.Calculate the % purity of the sample (MAgnesium = 24,Hydrogen = 1)

A circular cylinder of radius R and height H is filled with water to a height (2/3)H. It starts rotating with constantly increasing angular speed.

Choose the correct alternatives

a) At all speeds, shape of the free surface is parabolloid

b) The free surface touches first the brim of the cylinder and then the base of the cylinder

c) The free surface cannot touche the brim of the cylinder without spilling water

d) The free surface touches the brim of the cylinder as well as the base of the cylinder simultaneously

Answer a,b,c

Kindly explain

In the isoelectronic series of metal carbonyl, the CO bond length is expected to increase in the order

[V(CO)₆]^- < [Cr(CO)₆] < [Mn(CO)₆]⁺

Kindly explain

A particle of mass m is attached to a massless string of length l and is oscillating in a vertical plane with the other end of the string fixed to a rigid support.

The tension in the string at a particular instant is kmg.

a) k can never be greater than 1

b) k can never be less than 1

c) k can never be equal to 1

d) k can never be greater than 3

Answer d.

Kindly explain

An expansible balloon filled with 2/3 of its volume is submerged in water. How deep should it be sunk in water, in order that it is just in equilibrium, neither sinking nor rising further? Height of water barometer = 10m.

Answer 5m.

Kindly explain

The number of unordered pairs of disjoint subset of the set s = {1,2,3,4} is 

Ans 41. Kindly explain.

Whether the following statement is true or false?

A solid sphere and a hollow sphere of same mass M and same radius R are released from the top of a rough inclined plane. Friction co-efficient is same for both the bodies. If both bodies perform imperfect rolling, then the work done by friction for the motion of bodies from top of incline to the bottom will be same for both the bodies.

Answer is given as FALSE.  Please explain.

Q. The change in Gibbs free energy of vapourisation of 1mol of H2O at  1atm and 100deegre celcius is (q is heat change at constant pressure)

a) q

b) -TdeltaS

c) 0

d) 2q

pls tell