52. On keeping sodium hydroxide in open vessel, the weight
of solution would
(1) Increase
(2) Decrease
(3) Not change
(4) Either (1) or (2)
53. The ore which contains both magnesium and calcium is
(1) Dolomite
(2) Magnesite
(3) Carnailite
(4) Phosphorite
54. Wire of flash bulb is made up of
(1) Mg
(2) Cu
(3) Ba
(4) Ag
55. Excess of Nations in human body results in
(1) Low blood pressure (2) High blood pressure
(3) Diabetes
(4) Anaemia
56. Which of the following is soluble in water?
(1) All carbonates
(2) Carbonates of Ca, Sr, Ba
(3) Carbonates of Na, K and NH;
(4) All sulphates
Answers
Answer:
52
answer (3)
the weight will remains same it don't change
as Solid NaOH is very hygroscopic, that is it absorbs water from the air, so it is very hard to weigh exactly. This decreases the concentration of the OH- ions in the solution..
53
option (1)
dolomite contains both calsium and magnesium
as it's formula is MgCO3.CaCO3
54
option (1)
The first modern photoflash bulb (or flashbulb) was made by Austrian Paul Vierkotter, who used magnesium coated wire in an evacuated glass globe. It was later determined that aluminum foil in a low pressure oxygen atmosphere worked even better, and was cheaper to produce.
55
option (2)
Answer:
52.(1) increase. 53.(1) Dolomite. 54.(1)Mg. 55.(2) High Blood pressure. 56.(2)
Explanation:
52.(1) NaOH is hydroscopic, i.e. it absorbs water when kept in an open vessel. So the weight of solution would increase.