Chemistry
Write true or false for the following and correct the false statements.
(a) When iron nails are put into a solution of copper sulphate, the solution becomes colourless after sometime.
(b) Burning of fuel in air produces a large amount of energy in the form of heat and light.
(c) Exchange of radicals takes place when calcium oxide reacts with water.
(d) A neutral oxide does not change the colour of an indicator.
(e) A white solid is produced when lead nitrate is heated.
Chemical Reaction
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Answer
(a) False
Correct Statement — When iron nails are put into a solution of copper sulphate, the solution becomes light green after sometime.
(b) True
(c) False
Correct Statement — Calcium oxide reacts with water to form calcium hydroxide; it is a combination reaction, not an exchange (double displacement) reaction.
(d) True
(e) False
Correct Statement — A pale yellow solid and reddish brown gas is produced when lead nitrate is heated.
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Related Questions
Assertion (A): When energy is absorbed during a chemical reaction, it is said to be an exothermic reaction.
Reason (R): A rise in temperature takes place during an exothermic reaction.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Fill in the blanks:
(a) A reaction in which two or more substances combine to form a single substance is called a …………… reaction.
(b) A …………… is a substance which changes the rate of a chemical reaction without undergoing a chemical change itself.
(c) The formation of gas bubbles in a liquid during a reaction is called …………… .
(d) The reaction between an acid and a base is called …………… .
(e) Soluble bases are called …………… .
(f) The chemical change involving iron and hydrochloric acid illustrates a …………… reaction.
(g) In the type of reaction called …………… two compounds exchange their positive an negative radicals respectively.
(h) A catalyst either …………… or …………… the rate of a chemical change but itself remains …………… at the end of the reaction.
(i) The chemical reaction between hydrogen and chlorine is a …………… reaction.
(j) When a piece of copper is added to silver nitrate solution, it turns …………… in colour.
Match the following :
Column A Column B (a) It changes the rate of a chemical reaction (i) Photosynthesis (b) Attractive force between the atoms to form molecules (ii) Amphoteric oxide (c) Oxides of non-metals (iii) Catalyst (d) Lead monoxide (iv) Chemical bond (e) Light energy (v) Acidic oxides Name the following :
(a) The substances formed due to a chemical reaction.
(b) An insoluble solid produced when two substances in solution form are mixed together.
(c) The compounds formed by the reaction between oxygen and any other element.
(d) The chemical reactions in which energy is released.
(e) A chemical reaction in which a substance breaks to give two or more simpler substances.