Answer:
1. Answer : (b) Liquid
Explanation: Hydrogen peroxide is the simplest kind of peroxide available (oxygen-oxygen single bond). It is a colourless liquid and is used in aqueous solution for safety reasons. It acts as a bleaching agent and is also used as a disinfectant.
2. Answer : (b) 90%
Explanation: H2O2 is used as an oxidant for rocket fuel. Usually, 90% concentration of H2O2 is used.
3. Answer : (a) Ionic Hydrides
Explanation: Intersetitial hydrides are non- stochiometric hydrides and thus deficitn in hydrogen. Transition and innertransition elements at elevant temp. absorb hydrogen into the interstices of their lettices to yield metal like hydrides.
4. Answer : (b) HCl + O2
Explanation: H2O2 + Cl2 → 2HCl + O2
5. Answer : (b) CO2
Explanation: Water gas is a mixture of carbon monoxide and hydrogen produced from synthesis gas. Synthesis gas is a useful product, but requires careful handling due to its flammability and the risk of carbon monoxide poisoning. The water-gas shift reaction can be used to reduce the carbon monoxide while producing additional hydrogen, resulting in water gas.
6. Answer : (c) Black Suspension of Lead Sulphide(PbS)
Explanation: Lead sulphide (black suspension) on reaction with hydrogen peroxide forms lead sulphate and water. Lead sulphate as well as water are colourless, therefore lead sulphite decolourises on addition of hydrogen peroxide.
7. Answer : (a) Oxygen
Explanation: The mass-abundance of the nine most abundant elements in the Earths crust is approximately: oxygen 46%, silicon 28%, aluminium 8.2%, iron 5.6%, calcium 4.2%, sodium 2.5%, magnesium 2.4%, potassium, 2.0%, and titanium 0 .61%.
8. Answer : (b) 50 ml
Explanation: As 10 ml of oxygen is obtained at STP from H2O2 = 1 ml
Therefore, 500 ml of O2 is obtained at STP = 50 ml
9. Answer : (a) at very high pressure
Explanation: Metallic hydrogen is a phase of hydrogen when it behaves as electrical conductor. At the high pressure of giga pascals hydrogen exist as a liquid metal. Liquid metallic hydrogen is thought to be present in large amount in gravitationally compressed interiors of Jupiter and Saturn.
10. Answer : (a) its non-metallic character
Explanation: Hydrogen is a non-metal while all other members of group 1 (alkali metals) are metals.
11. Answer : (a) halogen
Explanation: Hydrogen accepts an electron to form inert gas configuration. In this, it resembles halogen as like halogen it gains 1 electron and attains noble gas configuration.
12. Answer : (a) 3-10 kcals
Explanation: Hydrogen bond is weak force of attraction existing between molecules. Its energy is equal to 3−10 kcal
13. Answer : (a) Copper and HCl (aqueous)
Explanation: Since copper is placed below hydrogen in the electrochemical series, thus copper does not give hydrogen with dilute acids. While all other pairs give hydrogen on reaction.
14. Answer : (a) Mg
Explanation: Only magnesium and manganese react with nitric acid to release hydrogen gas. So, option A is correct. Hydrogen gas is not evolved when other metals react with nitric acid because it is a strong oxidising agent. It oxidises hydrogen produced to water and itself gets reduced to a nitrogen oxide.
15. Answer : (a) Mn
Explanation: Mg and Mn liberates H2 from dilute HNO3.
16. Answer : (a) Cold water
Explanation: Zinc has no action on cold water.
17. Answer : (b) 0°
Explanation: In eclipsed conformation ( the least stable conformation), the two C-H bonds are parallel, i.e., the four atoms H-C-C-H lie in the same plane. In this position, the dihedral angle ( also called the angle of rotation or the angle of torsion or torsional angle) is zero degree.
18. Answer : (a) Hydrogenation
Explanation: The reaction is known as hydrogenation reaction. When vegetable oils are treated with hydrogen and passed over finely divided nickel or palladium at 200∘C, the hydrogen molecules are added to the unsaturated carbon-carbon bonds hence, saturated vegetable fats are obtained.
19. Answer : (b) van der Waals
Explanation: A hydrogen bond is a strong intermolecular force, but in solid hydrogen weak Van der Waal's forces are present as molecular solids consist of small non-polar covalent molecules and is held by London dispersion or Van der Waal's forces.
20. Answer : (a) C2D2
Explanation: CaC2 + D2O→ CD ≡ CD + Ca(OD)2
21. Answer : (b) Oxidising properties
Explanation: The bleaching action is due to the oxidizing nature. H2O2 → H2O + [O] Coloured matter + [O] → Colourless matter.
22. Answer : (a) Magnesium bicarbonate
Explanation: Chlorides and sulphates of Mg and Ca produces permanent hardness, and bicarbonates of Mg and Ca produces temporary hardness.
23. Answer : (c) Clark's method
Explanation: Water that contains bicarbonate of calcium and magnesium or of both is called temporary hard water and water that contains chlorides or sulphates of calcium or magnesium or of both is called Permanent water. -Therefore, the method used to remove temporary hardness of water is Clark's method.
24. Answer : (a) Hydrogen atoms with excess energy
Explanation: Nascent hydrogen consists of hydrogen molecules with excess energy. Nascent hydrogen is hydrogen in the form of single atoms, rather than hydrogen in the form of molecules, as it is in the gaseous state. Individual hydrogen atoms or ions are extremely reactive.
25. Answer: (c) H2O2
Explanation: The lead of oil paintings gets converted into lead sulphide by atmospheric H2S leading to blackening of paintings. Hydrogen peroxide (H2O2) oxidises the black lead sulphide into white lead sulphate, thus restores the colour of oil paintings.
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