Advertisements
Advertisements
प्रश्न
Fill in the blanK
A .............is a substance which changes the rate of a chemical reaction without undergoing a chemical change.
Advertisements
उत्तर
A catalyst is a substance which changes the rate of a chemical reaction without undergoing a chemical change.
APPEARS IN
संबंधित प्रश्न
What are (i) positive catalysts and (ii) negative catalysts? Support your answer with one example for each of them.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Reduction is a chemical reaction in which there is
- removal of hydrogen
- removal of oxygen
- addition of oxygen
- none of these
What are the characteristics of a chemical reaction ? A chemical reaction is characterised by an irreversible change in which a new substance is formed.
Give an example of a reaction where the following are involved:
Close contact
When hydrogen burns in oxygen, water is formed; when electricity is passed through water, hydrogen and oxygen are given out. Name the type of chemical change involved in the two cases.
Explain,giving one example of the following chemical changes:
Reversible reaction
What is a chemical change? Give two examples of chemical change?
State the original colour of the following substance and colour of residue obtained after heating.
Ammonium dichromate
Distinguish by dilute sulphuric acid.
Copper and magnesium?
Give examples of exothermic reactions i.e. heat evolved in each of the following:
(a) reaction between a solid and a liquid
(b) reaction between two gases
Give two examples of exothermic reactions seen in everyday life.
Give reason for the following:
Electrolytic decomposition of water is a reaction involving change of state.
Give reason for the following:
A characteristic change of colour is seen when a piece of iron is added to copper [II] sulphate solution.
On heating which of the following substances i.e. copper carbonate, zinc carbonate, washing soda, copper sulphate, zinc nitrate, copper nitrate, lead nitrate, ammonium chloride and ammonium dichromate – relate to the reaction given below.
A coloured substance which leaves on strong heating a black residue and evolves two colourless gases one of which is acidic and the other neutral.
Give balanced equation for the following conversion affected by heat alone on the substance:
Zinc carbonate to zinc oxide
Complete the table given below.
| Heat on copper carbonate | Test for gas evolved |
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Lead nitrate.
______ change results in the change of the substance.
Which of the following is a chemical change?
Write word equations for two chemical reactions with the help of materials given in the box.
| Air, copper sulphate, iron, vinegar, iron oxide, carbon dioxide, iron sulphate, copper, lime water, water |
