Fill in the blanks
1. Complete the following statements.
[1 Mark each]
i. The composition of matter remains the same in a ___________change.
ii. The reaction in which there is only one reactant giving rise to two or more products is called a ____________reaction.
iii. Hydrogen peroxide undergoes slow
decomposition into __________and oxygen
iv. The chemical formula of potassium chromate is ___________.
v. "The melting of ice is an _________process.
vi. In our body, _________increase the rate of
physiological reactions.
vii. The ________layer in the earth's atmosphere protects the life on earth. from the harmful ultraviolet radiations of the sun.
viii. The chemical process in which the. positive charge on an atom or an ion increases or the negative charge on. them decreases is called __________.
ix. A ________reaction takes place during. cellular respiration, where the molecule of the. enzyme called cytochrome C. oxidase helps in the transport of. electron.
x. The chemical formula of rust is _________.
xi. Rancidity in the food stuff cooked in oil or ghee is prevented by using ___________.
xii. The process of ________reaction of food. stuff. can also be slowed down by storing it. in air tight container
Answers:
i. physical
ii. decomposition
iii. water
iv. K Cr04
V. endothermic vi. enzymes
vii. ozone
viii. Oxidation
ix. redox
x. Fe 03 xH2O
xi. Antioxidants
xii. oxidation
xii. oxidation
2. Select the appropriate options and. complete the following paragraph.
[3 Marks]
(oxygen, hydrogen, reduction, oxidation, never, always, redox, decomposition)
________is the process in which a substance gains ___________or loses hydrogen. _______ is the process in which a substance gains __________ or loses oxygen. The reaction in which one reactant gets oxidised and the other reactant gets reduced
is called as oxidation-reduction reaction or ___________ reaction. Oxidation and reduction reactions ____________occur simultaneously.
Answer:
Oxidation is the process in which a substance gains oxygen or loses hydrogen. Reduction is the process in which a substance gains hydrogen or loses oxygen. The reaction in which one reactant
gets oxidised and the other reactant or the same reactant gets reduced is called as oxidation- reduction reaction or redox reaction. Oxidation and reduction reactions always occur simultaneously.
Choose the correct alternative.
[1 Mark each]
1. _________is a chemical change.
(A) Ice changing to water
(B) Condensation of steam
(C) Sublimation of camphor
(D) Ripening of fruits
2. What happens when a piece of zinc. metal. is added to copper sulphate. solution?
(A) Copper sulphide is formed.
(B) Colourless solution of zinc sulphate is
formed.
(C) Copper sulphate solution is not affected
at all.
(D) Hydrogen sulphide gas is evolved.
3. When two or more reactants combine in. a reaction to form a single product, it is. called a ____________reaction.
(A) combination
(B) decomposition
(C) displacement
(D) double displacement
4. When _______is passed through fresh lime
water, it turns milky.
(A) H
(B) CO2
(C) CO
(D) SO
5. On mixing aqueous solutions of silver. nitrate and sodium chloride, a white. precipitate is obtained. This reaction can be categorized as _________reaction.
(A) decomposition
(B) combination
(C) displacement
(D) double displacement
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