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Write the chemical reactions involved in the extraction of gold by cyanide process. Also give the role of zinc in the extraction.
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Which of the following statements is wrong?
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The oxidation state of central atom in the anion of compound \[\ce{NaH2PO2}\] will be ______.
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If chlorine gas is passed through hot NaOH solution, two changes are observed in the oxidation number of chlorine during the reaction. These are :
(i) 0 to +5
(ii) 0 to +3
(iii) 0 to –1
(iv) 0 to +1
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Which of the following options are not in accordance with the property mentioned against them?
| (i) | \[\ce{F2 > Cl2 > Br2 > I2}\] | Oxidising power. |
| (ii) | \[\ce{MI > MBr > MC1 > MF}\] | Ionic character of metal halide. |
| (iii) | \[\ce{F2 > Cl2 > Br2 > I2}\] | Bond dissociation enthalpy. |
| (iv) | \[\ce{HI < HBr < HCI < HF}\] | Hydrogen-halogen bond strength. |
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Which of the following statements are correct for \[\ce{SO2}\] gas?
(i) It acts as bleaching agent in moist conditions.
(ii) It’s molecule has linear geometry.
(iii) It’s dilute solution is used as disinfectant.
(iv) It can be prepared by the reaction of dilute \[\ce{H2SO4}\] with metal sulphide.
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Which of the following orders are correct as per the properties mentioned against each?
| (i) | \[\ce{As2O3 < SiO2 < P2O3 < SO2}\] | Acid strength. |
| (ii) | \[\ce{AsH3 < PH3 < NH3}\] | Enthalpy of vapourisation. |
| (iii) | \[\ce{S < O < Cl < F}\] | More negative electron gain enthalpy. |
| (iv) | \[\ce{H2O > H2S > H2Se > H2Te}\] | Thermal stability. |
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Match the species given in Column I with the shape given in Column II and mark the correct option.
| Column I | Column II |
| (A) \[\ce{SF4}\] | (1) Tetrahedral |
| (B) \[\ce{BrF2}\] | (2) Pyramidal |
| (C) \[\ce{BrO^{-}3}\] | (3) Sea-saw shaped |
| (D) \[\ce{NH^{+}4}\] | (4) Bent T-shaped |
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Match the items of Columns I and II and mark the correct option.
| Column I | Column II | |
| (A) | Its partial hydrolysis does not | (1) He |
| (B) | It is used in modern diving apparatus | (2) XeF6 |
| (C) | It is used to provide inert atmosphere for filling electrical bulbs |
(3) XeF4 |
| (D) | Its central atom is in sp3d2 hybridisation | (4) Ar |
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Assertion: N2 is less reactive than P4.
Reason: Nitrogen has more electron gain enthalpy than phosphorus.
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Salvarsan is arsenic-containing drug which was first used for the treatment of ______.
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In \[\ce{PCl5}\], phosphorus is in sp3d hybridised state but all its five bonds are not equivalent. Justify your answer with reason.
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Arrange the following in the increasing order of their property indicated:
Benzoic acid, Phenol, Picric acid, Salicylic acid (pka values).
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Account for the following:
Zinc is a comparatively a soft metal, iron and chromium are typically hard.
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For the reaction, \[\ce{A +2B → AB2}\], the order w.r.t. reactant A is 2 and w.r.t. reactant B. What will be change in rate of reaction if the concentration of A is doubled and B is halved?
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The number of ions formed on dissolving one molecule of FeSO4.(NH4)2SO4.6H2O in water is ______.
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Identify the order of reaction from the following unit for its rate constant:
L mol–1 s–1
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The conversion of molecules A to B follow second order kinetics. If concentration of A is increased to three times, how will it affect the rate of formation of B?
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Which acid of the following pair would you expect to be stronger?
F−CH2−COOH or CH3−COOH
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Read the following passage and answer the questions that follow:
|
The rate of reaction is concerned with decrease in the concentration of reactants or increase in the concentration of products per unit of time. It can be expressed as instantaneous rate at a particular instant of time and average rate over a large interval of time. A number of factors such as temperature, concentration of reactants, catalyst affect the rate of reaction. Mathematical representation of rate of a reaction is given by rate law: Rate = k[A]x [B]y x and y indicate how sensitive the rate is to change in concentration of A and B. Sum of x + y gives the overall order of a reaction. |
- What is the effect of temperature on the rate constant of a reason? [1]
- For a reaction \[\ce{A + B → Product}\], the rate law is given by, Rate = k[A]2 [B]1/2. What is the order of the reaction? [1]
- How order and molecularity are different for complex reactions? [1]
- A first-order reaction has a rate constant 2 × 10–3 s–1. How long will 6 g of this reactant take to reduce to 2 g? [2]
OR
The half-life for radioactive decay of 14C is 6930 years. An archaeological artifact containing wood had only 75% of the 14C found in a living tree. Find the age of the sample.
[log 4 = 0.6021, log 3 = 0.4771, log 2 = 0.3010, log 10 = 1] [2]
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