Exercise : Solutions of Questions on Page Number : 197 Q1 : Which of the following cannot be charged easily by friction? (a) A plastic scale (b) A copper rod (c) An inflated balloon (d) A woollen cloth Answer : (b) A copper rod Only non-conducting materials can be easily charged by friction. Copper is a highly conducting materials. Therefore, a copper rod cannot be charged easily by friction. Q2 : When a glass rod is rubbed with a piece of silk cloth the rod (a) and the cloth both acquire positive charge. (b) becomes positively charged while the cloth…
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Exercise : Solutions of Questions on Page Number : 180 Q1 :Fill in the blanks. (a) Most liquids that conduct electricity are solutions of ________, _______ and ________. (b) The passage of an electric current through a solution causes _________ effects. (c) If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the __________ terminal of the battery. (d) The process of depositing a layer of any desired metal on another material by means of electricity is called _________. Answer : (a) Most liquids that conduct electricity are solutions of __acids__, __bases__ and __salts__.…
Exercise : Solutions of Questions on Page Number : 168 Q1 :Choose the correct answer. Sound can travel through (a) gases only (b) solids only (c) liquids only (d) solids, liquids and gases. Answer : (d) Sound can travel through solids, liquids, and gases. Sound requires a medium to travel through. Solid, liquid and gas provide the medium for sound. Hence, sound can travel through solids, liquids and gases. Q2 :Which of the following voices is likely to have minimum frequency? (a) Baby girl (b) Baby boy (c) A man (d) A woman Answer : (c) A man The voice…
Exercise : Solutions of Questions on Page Number : 155 Q1 : Fill in the blanks. (a) Friction opposes the ________between the surfaces in contact with each other. (b) Friction depends on the _________of surfaces. (c) Friction produces _________. (d) Sprinkling of powder on the carrom board ________friction. (e) Sliding friction is ________than the static friction. Answer : (a) Friction opposes the __motion__between the surfaces in contact with each other. (b) Friction depends on the __nature__of surfaces. (c) Friction produces __heat__. (d) Sprinkling of powder on the carrom board __reduces__friction. (e) Sliding friction is __less__than the static friction. Q2 :…
Exercise : Solutions of Questions on Page Number : 142 Q1 : Give two examples each of situations in which you push or pull to change the state of motion of objects. Answer : Two examples of push force are as follows: (i) A heavy box at rest is pushed to move it from one room to another. This changes the state of motion of the box. (ii) A player pushes a football using his foot. This changes the state of motion of the ball. Two examples of pull force are as follows: (i) Rope is pulled to draw water…
Exercise : Solutions of Questions on Page Number : 124 Q1 : What is the term used for secretions of endocrine glands responsible for changes taking place in the body? Answer : Hormones are chemical substances which are secreted by endocrine glands. They are responsible for changes taking place in the body. Q2 : Define adolescence. Answer : Adolescence is the time period between the beginning of puberty and adulthood. During this period, the body undergoes several changes alongside reproductive maturity. It begins around the age of 11 and lasts till 18 or 19 years of age. The period of…
Exercise : Solutions of Questions on Page Number : 110 Q1 : Explain the importance of reproduction in organisms. Answer : Reproduction is a biological process through which living organisms produce offspring similar to themselves. Living organisms reproduce to maintain their number and for the continuation of their species. Thus, reproduction ensures the continuation of similar kinds of individuals. Q2 : Describe the process of fertilization in human beings. Answer : Fertilization involves the fusion of the male and the female gamete. The male and the female gametes are released from the male and the female reproductive organs. Sperms or…
Exercise : Solutions of Questions on Page Number : 98 Q1 : Indicate whether the following statements are True (T) or False (F). (a) Unicellular organisms have one-celled body. (T / F) (b) Muscle cells are branched. (T / F) (c) The basic living unit of an organism is an organ. (T / F) (d) Amoeba has irregular shape. (T / F) Answer : (a) Unicellular organisms have one-celled body. (T) (b) Muscle cells are branched. (F) (c) The basic living unit of an organism is an organ. (F) (d) Amoeba has irregular shape. (T) Q2 : Make a sketch…
Exercise : Solutions of Questions on Page Number : 86 Q1 : Fill in the blanks: (a) A place where animals are protected in their natural habitat is called a __ . (b) Species found only in a particular area are known as ______. (c) Migratory birds fly to far away places because of ____ _ changes. Answer : (a) A place where animals are protected in their natural habitat is called a sanctuary__. (b) Species found only in a particular area are known as __endemic__. (c) Migratory birds fly to far away places because of __climatic__ changes. Q2 :…
Exercise : Solutions of Questions on Page Number : 75 Q1 : List conditions under which combustion can take place. Answer : Combustion is a process of reaction of a substance with oxygen. There are certain conditions required for combustion to take place. They are: (i) Presence of a fuel (ii) Air (or oxygen) (iii) Ignition temperature (minimum temperature at which a substance catches fire) Q2 : Fill in the blanks: (a) Burning of wood and coal causes _______ __of air. (b) A liquid fuel used in homes is ___________. (c) Fuel must be heated to its ___________ before it starts…