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Riya08
@riya08
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Joined: Dec 29, 2021
Last seen: Mar 10, 2022
Topics: 0 / Replies: 2143
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Answer to: Which of the ores can be concentrated by magnetic separation method?

If the ore or the gangue can be attracted by the magnetic field, then the ore can be concentrated by the process of magnetic separation. The ores of i...

4 years ago
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Answer to: The length of the latus rectum of a parabola, whose vertex and focus are on the positive x–axis at a distance R and S (>R) respectively from the origin, is

Correct answer: (3) 4(S – R) Explanation: figure.png V → Vertex F → Focus VF = S - R So latus rectum = 4(S – R)

4 years ago
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Answer to: If the following system of linear equations 2x + y + z = 5 x – y + z = 3 x + y + az = b has no solution, then:

Correct answer: (4) a = , b ≠ Explanation: Here D = = 2(-a - 1) -1 (a - 1) + 1 + 1 = 1 - 3a D3 = = 2(-b - 3) - 1(b - 3) + 5(1 + 1) = ...

4 years ago
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Answer to: cosec 18° is a root of the equation

Correct answer: (4) x2 – 2x – 4 = 0 Explanation: cosec 18° = = = Let cosec 18° = x = ⇒ x - 1 = √5 Squaring both sides, we get x2 - 2...

4 years ago
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Answer to: If p and q are the lengths of the perpendiculars from the origin on the lines, x cosec α – y sec α = kcot 2α and x sin α + y cosα = k sin 2α respectively, then k2 is equal to :

Correct answer: (1) 4p2 + q2 Explanation: First line is - = ⇒ xcosα - ysinα = cos2α ⇒ p = ⇒ 2p = |kcos2α| .....(i) second line is xsi...

4 years ago
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Answer to: Comment on the statement that "colloid is not a substance but a state of substance".

Common salt (a typical crystalloid in an aqueous medium) behaves as a colloid in a benzene medium. Hence, we can say that a colloidal substance does n...

4 years ago
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Answer to: Explain the terms with suitable examples: (i) Alcosol (ii) Aerosol (iii) Hydrosol

(i) Alcosol: A colloidal solution having alcohol as the dispersion medium and a solid substance as the dispersed phase is called an alcosol. For ex...

4 years ago
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Answer to: Give four uses of emulsions.

Four uses of emulsions: (i) Cleansing action of soaps is based on the formation of emulsions. (ii) Digestion of fats in intestines takes place b...

4 years ago
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Answer to: Give four uses of emulsions.

Four uses of emulsions: (i) Cleansing action of soaps is based on the formation of emulsions. (ii) Digestion of fats in intestines takes place b...

4 years ago
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Answer to: Explain the following terms: (i) Electrophoresis (ii) Coagulation (iii) Dialysis (iv) Tyndall effect.

(i) Electrophoresis: The movement of colloidal particles under the influence of an applied electric field is known as electrophoresis. Positively char...

4 years ago
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Answer to: What is shape selective catalysis?

A catalytic reaction which depends upon the pore structure of the catalyst and on the size of the reactant and the product molecules is called shape-s...

4 years ago
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Answer to: Describe some features of catalysis by zeolites.

Zeolites are alumino-silicates that are micro-porous in nature. Zeolites have a honeycomb-like structure, which makes them shape-selective catalysts. ...

4 years ago
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Answer to: What do you mean by activity and selectivity of catalysts?

(a) Activity of a catalyst: The activity of a catalyst is its ability to increase the rate of a particular reaction. Chemisorption is the main factor ...

4 years ago
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Answer to: Give four examples of heterogeneous catalysis.

(i) Oxidation of sulphur dioxide to form sulphur trioxide. In this reaction, Pt acts as a catalyst. 2SO2(g) 2SO3(g) (ii) Formation of ammonia by ...

4 years ago
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Answer to: Action of soap is due to emulsification and micelle formation. Comment.

The cleansing action of soap is due to emulsification and micelle formation. Soaps are basically sodium and potassium salts of long chain fatty acids,...

4 years ago
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Answer to: What is demulsification? Name two demulsifiers.

The process of decomposition of an emulsion into its constituent liquids is called demulsification. Examples of demulsifiers are surfactants, ethylene...

4 years ago
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Answer to: What are emulsions? What are their different types? Give example of each type.

The colloidal solution in which both the dispersed phase and dispersion medium are liquids is called an emulsion. There are two types of emulsions:...

4 years ago
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Answer to: Explain what is observed (i) When a beam of light is passed through a colloidal sol. (ii) An electrolyte, NaCl is added to hydrated ferric oxide sol.

(i) When a beam of light is passed through a colloidal solution, then scattering of light is observed. This is known as the Tyndall effect. This scatt...

4 years ago
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Answer to: How are colloids classified on the basis of (i) Physical states of components (ii) Nature of dispersion medium and

Colloids can be classified on various bases: (i) On the basis of the physical state of the components (by components we mean the dispersed phase an...

4 years ago
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Answer to: What are enzymes? Write in brief the mechanism of enzyme catalysis.

Enzymes are basically protein molecules of high molecular masses. These form colloidal solutions when dissolved in water. These are complex, nitrogeno...

4 years ago
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