fluid mechanics

1.To construct a barometer a tube of length 1m is completely filled with mercury and is inverted in a mercury cup.The barometer reading on a particular day is 76 cm.suppose a i m tube is filled with mercury up to 76 cm and then closed by the cork. It is inverted in a mercury cup and the cork is removed. The height of the mercury column in the tube over the surface in the cup will be
(a)zero (b)76cm (c)>76cm (d)<76cm
2.A metal cube is placed in an empty vessel. When water is filled in the vessel so that the cube is completely immersed in the water,the force on the bottom of the vessel in contact with the cube
(A) will increase (B)will decrease (C)will remain same (D) will become zero
3.The weight of the empty balloon on a spring balance is W₁. The weight becomes W₂ when the balloon is filled with air. Let the weight of the air itself be w. Neglect the thickness of the balloon when it is filled with air. Also neglect the difference in the densities of air inside and outside the balloon.
(a) W₂=W₁
(b)W₂=W₁ + w
(c)W₂<W₁ +w
(d)W₂>W₁
4.Water flows through two identical tubes A and B. A volume V₀ of water passes through the tube A and 2V₀ through B in a given time. Which of the following may be correct?
(A) Flow in both tube are steady
(B) Flow in both tube are turbulent
(C)Flow is steady in A but turbulent in B
(D)Flow is steady in B but turbulent in A

Ans :- 1. (d) 2.(C) 3.(a), (c) 4. (a), (b) and (C)