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प्रश्न
Define the following term:
Hygroscopy
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उत्तर
It is the phenomenon by which substances absorb moisture from air, but only sufficiently so as to become wet.
संबंधित प्रश्न
State what would you observe when Washing Soda Crystals are exposed to the atmosphere
From the list of the following salts choose the salt that most appropriately fits the
description is given in the following:
[AgCl, MgCl2, NaHSO4, PbCO3, ZnCO3, KNO3, Ca(NO3)2]
On heating, this salt gives a yellow residue when hot and white when cold
State whether the following statement is true or false:
Copper sulphate crystals are always wet due to the presence of water of crystallisation in them.
What are the two main ways in which common salt (sodium chloride) occurs in nature?
Fill in the following blank:
Rock salt is mined just like ......................
Name three products of the chlor-alkali process. State two uses of each of these products.
Write the names, formulae and colours of any two hydrated salts.
What will be the colour of litmus in an aqueous solution of ammonium chloride salt?
The products of chlor-alkali process are:
(a) NaCl, Cl2 and H2
(b) H2, Cl2 and NaOH
(c) Cl2, Na2CO3 and H2O
(d) NaOH, Cl2 and HCl
P and Q are aqueous solutions of sodium chloride and sodium hydroxide, respectively. Which of these will turn:
(a) blue litmus red?
A salt X when dissolved in distilled water gives a clear solution which turns red litmus blue. Explain the phenomenon.
name two salts which are basic.
You are asked to prepare hard water in your laboratory. Select a group from the following groups of salts, any salt of which you may dissolve in distilled water to obtain hard water.
(A) NaCl; Na2SO4; KCl
(B) NaCl; CaCl2; KCl
(C) CaCl2; CaSO4; MgSO4
(D) Na2SO4; CaSO4; MgSO4
State one observation for each of the following :
Lead nitric is heated strongly in a test tube.
State what would you observe when :
Washing soda crystals are exposed to the atmosphere.
Name two carbonates which do not produce carbon dioxide on heating.
Copy and complete the following table which refers to the action of heat on some carbonates:
| Carbonate | Colour of residue on cooling |
| Zinc Carbonate | |
| Lead carbonate | |
| Copper carbonate |
Distinguish by a chemical test sodium chloride and sodium sulphide.
Salts A, B, C, D and E undergo reactions (i) to (v) respectively. Identify the anion present in these salts on the basis of these reactions.
- When silver nitrate solution is added to a solution of A, a white precipitate, insoluble in dilute nitric acid, is formed.
- The addition of dilute hydrochloric acid to B produces a gas which turns lead acetate black on paper.
- When a freshly prepared solution of ferrous sulphate is added to a solution of C and concentrated sulphuric acid is gently poured from the side of the test tube, a brown ring is formed.
- When dilute sulphuric acid is added to D, a gas is produced which turns acidified potassium dichromate solution from orange to green.
- The addition of dilute hydrochloric acid to E produces effervescence. The gas produced turns lime water milky but does not affect acidified potassium dichromate solution.
The chemical name of plaster of Paris is ______.
