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प्रश्न
The atoms of which of the following pair of elements are most likely to exist in free state ?
पर्याय
hydrogen and helium
argon and carbon
neon and nitrogen
helium and neon
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उत्तर
helium and neon
Atoms of helium and neon exist in a free state because they are inert gases and chemically inactive.
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संबंधित प्रश्न
Give the symbols and valencies of following radicals:
(a) Hydroxide (b) Chloride
(c) Carbonate (d) ammonium
(e) Nitrate
Write true or false
Milk is an emulsion.
Why is the symbol S for sulphur, but Na for sodium and Si for silicon?
Match the metallic elements – with their correct symbols Metallic elements
| Metallic elements | Symbol |
| (a) Potassium | (1) Ca |
| (b) Sodium | (2) Zn |
| (c) Calcium | (3) Pb |
| (d) Magnesium | (4) Hg |
| (e) Zinc | (5) Cu |
| (f) Aluminum | (6) Au |
| (g) Iron | (7) K |
| (h) Lead | (8) Fe |
| (i) Copper | (9) Al |
| (j) Mercury | (10) Na |
| (k) Silver | (11) Mg |
| (l) Platinum | (12) Pt |
| (m) Gold | (13) Ag |
Give the symbol and the number of atoms of the following elements present in sodium chloride.
Match the symbols of metallic elements – with their correct combining power or capacity.
(a) K
(b) Zn
(c) Al
(d) Na
(e) Ca
Combining power or capacity – A : 3 ; B : 2 ; C : 1. (positive valencies)
Write the radical of the following valency:
Carbonate
Give the formula of the following gas:
Ammonia
State whether the following ion or radical given below of a non-metallic element exhibits valency: 1–, 2– or 3–. (write the ion or radical with the correct valency).
Bisulphite
Write the symbols for the following elements.
- Oxygen
- Gold
- Calcium
- Cadmium
- Iron
