EASY
9th Kerala Board
IMPORTANT
Earn 100

Sulphur pieces do not react with cold concentrated nitric acid. But sulphur powder reacts. Explain the reason why the rate of chemical reaction is increased here?

Important Questions on Redox Reactions and Rate of Chemical Reactions

MEDIUM
9th Kerala Board
IMPORTANT
Chemistry Standard IX Part 1>Chapter 3 - Redox Reactions and Rate of Chemical Reactions>Let us assess>Q 3

Sulphur pieces do not react with cold concentrated nitric acid. But sulphur powder reacts.

Suppose you want to increase the rate of reaction again. Which way you would choose? Give reason.

EASY
9th Kerala Board
IMPORTANT
Chemistry Standard IX Part 1>Chapter 3 - Redox Reactions and Rate of Chemical Reactions>Let us assess>Q 4
Small amounts of phosphoric acid is usually added to hydrogen peroxide to prevent its decomposition. What is the function of phosphoric acid here?
EASY
9th Kerala Board
IMPORTANT
Chemistry Standard IX Part 1>Chapter 3 - Redox Reactions and Rate of Chemical Reactions>Let us assess>Q 4
Small amounts of phosphoric acid is usually added to hydrogen peroxide to prevent its decomposition. By which name are these type of substances known?
EASY
9th Kerala Board
IMPORTANT
Chemistry Standard IX Part 1>Chapter 3 - Redox Reactions and Rate of Chemical Reactions>Let us assess>Q 4
Small amounts of phosphoric acid is usually added to hydrogen peroxide to prevent its decomposition. Which substance would you add to increase the rate of decomposition of hydrogen peroxide?
HARD
9th Kerala Board
IMPORTANT
Chemistry Standard IX Part 1>Chapter 3 - Redox Reactions and Rate of Chemical Reactions>Extended activities>Q 1
Find the oxidation number of the elements which are underlined in the compounds given below. Among these find out the elements which show variable oxidation numbers.
Mn___O2, Mn2___O7, K2Cr2__O7, KCr__O3, Mn___Cl2, Mg___O, Mg___Cl2, Al2__O3, Al__Cl3 
(Hint. Oxidation number O=-2, Cl=-1, K=+1)
HARD
9th Kerala Board
IMPORTANT
Chemistry Standard IX Part 1>Chapter 3 - Redox Reactions and Rate of Chemical Reactions>Extended activities>Q 2
Some apparatus and chemicals are given.
Zn, Mg, dilute HCl, CaCO3, test tube, water.
a) Design an experiment to prove that the nature of reactants can influence the rate of reaction.
b) Write the equations for the chemical reactions.
c) Write the expression for the rate of the reaction.
MEDIUM
9th Kerala Board
IMPORTANT
Chemistry Standard IX Part 1>Chapter 3 - Redox Reactions and Rate of Chemical Reactions>Extended activities>Q 3
The experiments conducted by two students are given below.
Experiment I:  2 ml of sodium thiosulphate solution is taken in a test tube, heated and to it 2 ml of HCl solution is added.
Experiment II: 2 ml of sodium thiosulphate solution is taken in a test tube and to it 2 ml of HCl solution is added.
a) In which experiment is the precipitate formed quickly? Justify your answer.
b) Write the balanced equation for the reaction.
MEDIUM
9th Kerala Board
IMPORTANT
Chemistry Standard IX Part 1>Chapter 3 - Redox Reactions and Rate of Chemical Reactions>Extended activities>Q 4
Some materials available in the laboratory are given below. Magnesium ribbon, marble powder, marble pieces, dilute HCl, concentrated HCl.
a) Which materials will you choose for the preparation of more CO2 in less time?
b) Write the balanced chemical equation of the reaction.