question_answer4) During the preparation of hydrogen chloride gas on a humid day, the gas is usually passed through the guard tube containing calcium chloride. What is the role of calcium chloride taken in the guard tube?View Answer play_arrow
question_answer14) Two students perform the experiments on series and parallel combinations of two given resistors and and the following graphs are obtained. Which of the graph is/are correctly labelled in terms of the words series and parallel? Justify your answer.View Answer play_arrow
question_answer15) (a) When a white powder was mixed with dilute acid, a colourless and odourless gas was produced which turned lime water milky. What is this white powder? (b) Which one of the following set ups is the most appropriate for the evolution of hydrogen gas and its identification?View Answer play_arrow
question_answer16) A teacher gave two test tubes, one containing water and the other containing sodium hydroxide solution, to the students and asked them to identify the test tube containing sodium hydroxide solution. Which substance can be used to identify the test tube? Give the test.View Answer play_arrow
question_answer17) (a) A student took four test tubes containing solutions of different colours marked I, II, III and IV as shown below. Which test tubes could be containing copper sulphate solution and ferrous sulphate solution? (b) A student performed the following four experiments. In which experiments, would he find the formation of a solid deposition?View Answer play_arrow
question_answer18) This activity proves and shows that living plants absorb water from the soil and water gets transported to the leaves and loss of water takes place by leaves i.e., transpiration. Based on the above activity, give the answers of the following questions. (a) Why transpiration is necessary for the plants? (b) What is transpiration pull?View Answer play_arrow
question_answer31) During the reaction of some metals with dilute hydrochloric acid, following observations were made (a) Silver metal does not show any change. (b) The temperature of the reaction mixture rises when aluminium (Al) is added. (c) The reaction of sodium metals is found to be highly explosive. (d) Some bubbles of a gas are seen when lead (Pb) is reacted with the acid. (e) A gas is produced when sodium carbonate is added to the acid. Explain these observations giving suitable reasons. Or Write chemical equations representing each of (a) combination reaction. (b) thermal decomposition reaction. (c) double displacement reaction. (d) neutralization reaction. e) redox reaction.View Answer play_arrow
question_answer32) Yashoda makes potato chips for Kishan and stores them in a pot. She sees after sometime, that the chips got spoiled. She was disappointed and then Kishan told her, how this happened? (a) State values of Yashoda. (b) Which values of Kishan must be praised? (c) How do you store food at home? Or Mitali got silver anklets made for her and kept them in cupboard. After a few days, when she took them out for wearing, their colour was changed. She went to her mother to tell her that they were fooled by jeweller. Her mother asked her reason to feel so and told her, why this happened? (a) Throw light on values of Mitali. (b) Which values of her mother must be praised? (c) Why did the colour of anklets change?View Answer play_arrow
question_answer33) Hamida says her father that food synthesized in leaf by plant is transported to various parts. To help him explain the mechanism of translocation in plants. Or Define the terms nutrition and nutrients. List one difference between holozoic nutrition and saprophytic nutrition. Give two examples of each of these two types.View Answer play_arrow
question_answer34) What is the relation between resistanced and current potential difference? Give SI unit of resistance. Draw graph for following data. Give two examples of conductors which obey Ohm's law.
question_answer35) Define electric circuit. Draw symbols for (a) bulb (b) battery (c) close plug key (d) ammeter and connect them to form a circuit. Or (a) The flow of current in a circular wire creates a magnetic field at its centre. How can existence of this field be detected? State the rule which helps to predict the direction of magnetic field. (b) Represent uniform magnetic field and non-uniform magnetic field using a diagram. What does the density of field lines in a region indicate?View Answer play_arrow
question_answer36) (a) Name the places of our country where fields of natural gas are found. Why is it called a clean fuel? Give two reasons. (b) Why is there so much emphasis on changing over from petrol/diesel driven automobiles to CNG driven vehicles. Or (a) (i) What conversion of energy takes place in wind mill? (ii) What is the minimum wind velocity required to obtain useful energy with a windmill? (iii) Give one limitation of windmill. (b) Hydro energy is an indirect source of solar energy. Justify.View Answer play_arrow
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