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Reyana09
@reyana09
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Joined: Nov 16, 2021
Last seen: Dec 29, 2021
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Answer to: Which is not obtained when metal carbides react with H2O?

Correct answer: (a) Al4C3 + H2O → CH ≡ CH Explanation: Al4C3 + 12H2O → 4Al(OH)3 + 3CH4

4 years ago
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Answer to: The difference of number of water molecules in gypsum and plaster of Paris is

Correct answer: (d) Explanation: Gypsum is CaSO4.2H2O, where as plaster of paris is CaSO4 No. of water = (2 - ) → or molecules.

4 years ago
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Answer to: For which one of the following minerals, the composition given is incorrect?

Correct answer: (c) Borax — (Na2B4O7.7H2O) Explanation: Borax is Na2B4O7.7H2O.

4 years ago
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Answer to: Which of the following reagents gives yellow precipitate for the following sequence (i) NaOH (ii) dil. HNO3 (iii) AgNO3?

Correct answer: (d) Explanation: Silver nitrate test is carried out to detect the type of halide ion in a given solution. The solution is first ac...

4 years ago
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Answer to: Which of the following will dissolve in water and give colour?

Correct answer: (b) CuCl2 Explanation: CuCl2 gives blue-green coloured aqueous solution.

4 years ago
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Answer to: S1: Methyl orange is suitable indicator for titration of strong acid and weak base. S2: Phenolphthalein is not suitable indicator for titration of acetic acid and NaOH.

Correct answer: (b) S1 is correct but S2 is incorrect. Explanation: Methyl orange indicator is used in the strong acid weak base titration. Phenol...

4 years ago
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Answer to: On heating novolac with formaldehyde which of the following polymers will form? (a) Melamine (b) Resin (c) Bakelite (d) Polystyrene

Correct answer: (c) Bakelite Explanation: Bakelite is a polymer made up of the monomers phenol and formaldehyde. This phenol-formaldehyde resin is...

4 years ago
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Answer to: S1: Frenkel defect is interstitial as well as vacancy effect. S2: In Frenkel defect, solids show colour because of F-centre.

Correct answer: (b) S1 is correct but S2 is incorrect. Explanation: In Frenkel Defect the smaller ion (usually cation) is dislocated from its norm...

4 years ago
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Answer to: S1: In Bohr’s model velocity of electrons increases with decrease in positive charge of nucleus as electrons are not held tightly. S2: Velocity decreases with an increase in principal quantum number.

Correct answer: (c) S1 is incorrect but S2 is correct. Explanation: v = 2.18 x As positive charge on the nucleus (Z) decreases, velocity will a...

4 years ago
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Answer to: S1: Ellingham diagram is used to check which metal oxide is to be reduced by which compound. S2: In Ellingham diagram as we move from left to right, ∆S always increases.

Correct answer: (b) S1 is correct but S2 is incorrect. Explanation: ∆H (enthalpy change) and the ∆S (entropy change) values for any chemical react...

4 years ago
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Answer to: How many electrons are present in 4f orbital of Gd^2+?

Correct answer: (a) 7 Explanation: Electronic configuration of Gd2+ is [Xe]4f7

4 years ago
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Answer to: By which of the following process deionized water can be obtained?

Correct answer: (b) Synthetic resin method Explanation: Pure de-mineralised (de-ionized) water free from all soluble mineral salts is obtained by ...

4 years ago
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Answer to: A rocket of mass 1000 kg starts by burning fuel at relative velocity 500 m/s. If it accelerates at a rate of 20 m/s^2, find the rate at which fuel is burning in kg/s.

Correct answer: (d) 60 kg/s Explanation: Mass of rocket (m) = 1000 kg Velocity v = 500 m/s Acceleration a = 20 m/s2 m(g + a) = v = = ...

4 years ago
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Answer to: List any three important characteristics of a population and explain.

The three important characteristics of a population are: (i) Birth and death rate (ii) Age structure (iii) Sex ratio (i) The birth rate (na...

4 years ago
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