Solution. Class 10 - Science. Revision test. Section A. produced only when HCl gas comes in contact with water. Therefore dry HCl do not

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1 Solution Class 10 - Science Revision test Section A 1. Colour of litmus paper changes only when it come in contact of H + ions and H + ions is produced only when HCl gas comes in contact with water. Therefore dry HCl do not change the colour of dry litmus paper. 2. An acidic oxide is an oxide which when combined with water gives a base. E.g. CO 2, SO 2 3. Substance Blue Litmus paper Red litmus paper Dry HCI gas None None Moistened NH3 gas None Turns blue 4. All substances that are basic in nature turn phenolphthalein indicator pink. Thus, solution 'A' is basic in nature as it turns phenolphthalein pink. Solution 'B' is an acid as it has made the solution colourless by neutralizing its basic nature. As soon as the solution becomes acidic while adding solution 'B' drop by drop, the colour of phenolphthalein changes from pink to colourless. 5. When a cold and concentrated solution of sodium chloride (brine) reacts with ammonia and carbon dioxide, sodium hydrogen carbonate and ammonium chloride are formed. Sodium hydrogen carbonate is only slightly soluble in water; it precipitates out as a solid. 6. The student can use other indicator; like phenolphthalein or methyl orange to check the acidity or alkalinity of particular solution. The student can also us turmeric power to check the solutions. It is mentioned that litmus paper is not available. So, we can assume that the laboratory may have other indicators. 7. Salt A is sodium hydrogen carbonate (baking soda). When it is heated, it turns into sodium carbonate; which is salt B. In this reaction, carbon dioxide gas is also Mob ALL THE BEST-- 1 / 12

2 produced; which is the gas C. Sodium hydrogen carbonate is used in bakery products. Sodium carbonate is used for removing hardness of water. 8. Hydrochloric acid HCl reacts with sodium carbonate Na 2 CO 3, forming sodium chloride NaCl, water H 2 O, and carbon dioxide CO 2. This equation is balanced as written: Na 2 CO 3 + 2HCl 2NaCl + H 2 O + CO 2 9. Rain water contains small amount of acids and dissolved salts. Acids ionise in rain water. It is because of the presence of ions that rain water conducts electricity. Distilled water is pure water. It does not contain any ionic compound like acids or bases or salts dissolved in it. Therefore, distilled water does not conduct electricity. 10. The contents of each test tube can identified as follows:- (i) Put the red litmus paper turn by turn in each of the three test tubes. The solution which turns the red litmus paper to blue will be a basic solution. Mark the test tube as 'B'. The blue litmus paper formed can now be used to test the acidic solution. (ii) Put the blue litmus paper in the remaining two test tubes, one by one. The solution which turns the blue litmus paper to red will be the acidic solution. Mark the test tube as 'A'. (iii) The solution which has no effect on any litmus paper will be neutral and hence, it will be distilled water. 11. The growth movement of tendril in response to unilateral stimulus of touch is called thigmotropism. Tendrils of louki, tori, karela, and sweet pea plants coil around hard objects when they come in their contact. It occurs due to unequal growth of two sides of a tendril. The growth of the surface which comes in contact of the support is retarded due to less auxin, while it remains normal or increased on the other side, due to which tendril coils around the support ) Follicular stimulating Hormone (FSH) - It stimulates the production of sperms in the testis. Mob ALL THE BEST-- 2 / 12

3 2) Interstitial stimulating hormone (ICSH) - It stimulates the interstitial cells of the testis and produce a male sex hormone known as 'testosterone'. The FSH and ICSH are secreted by pituitary gland. 13. (i) Brain: It is protected by the bony box-cranium inside the skull. A three layered membrane surround the brain (meninges) are filled with cerebrospinal fluid that act as shock absorbers protecting the brain. (ii) Spinal cord: The vertebral column, commonly called backbone, protect the spinal cord. 14. As a result of castration in male, the secondary sexual characters do not appear and sex instinct is suppressed. This shows that the testosterone hormone produced by the testes are responsible for the development of secondary sexual characters in males and also for the sexual behaviour in male cat. 15. The medulla oblongata is the most important part of the brain. Because the medulla oblongata helps regulate breathing, heart and blood vessel function, digestion, sneezing, and swallowing. This part of the brain is a center for respiration and circulation. 16. Chemical coordination in plants is maintained by plant hormones also known as phytohormones. Some of these hormones promote growth while some inhibit it. Some hormones include auxin, Gibberellins, Cytokinin that promotes growth while, hormones like absesic acid and ethylene inhibit the growth. 17. Autonomous nervous system includes sympathetic chain of ganglia, sympathetic and parasympathetic nerves. Autonomous nervous system controls and co-ordinates the activities of visceral organs. 18. The movement in stem and root towards light and gravtity of earth is due to grwoth.auxins (plant hormones) produced by the shoot apex and root tip. In stem, growth is more on the shaded side (lower side of apex) due to accumulation of auxins. In root, growth is more on the illuminated side. Auxins accumulate on the lower side (shaded side) of root tip inhibits the growth of that side. Thus, there is greater growth on the upper side (illuminated side), resulting in the growth of root apex towards gravity of earth. Mob ALL THE BEST-- 3 / 12

4 19. Sensory or Afferent nerves 1) Sensory nerves carry sensory impulses from receptor organs to the brain. 2) Impulses carried by sensory nerves result in sensation. 3) Sensory nerves are otherwise called afferent nerves. Motor or Efferent nerves 1) Motor nerves carry motor impulses from the brain to the effector organs. 2) Impulses carried by motor nerves result in some movements or actions. 3) Motor nerves are otherwise called efferent nerves. 20. The timing and the amount of hormones released by various glands controlled by the feedback mechanism which is inbuilt in glands. For example, if the sugar level in the blood rises too high, it is detected by cells of pancreas which respond by producing and secreting more insulin i blood. And as the blood sugar falls to a certain level, the secretion of insulin reduced automatically. Section B 21. Fix two nails on a cork and place it in a 100 ml beaker. Connect these nails to a 6 volt battery through a bulbs and switch as shown in the figure. Pour some aqueous solution of alcohol or aqueous solution of glucose in the beaker so that nails dip in it. Switch on the current. The bulb does not glow indicating that alcohol and glucose don't dissociate in aqueous solution and hence does not produce H + (aq) ions although they contain hydrogen. Mob ALL THE BEST-- 4 / 12

22. Chloride of lime is calcium hypochlorite [Ca(OCl) 2 ] which is alkaline. Calcium chloride is CaCl 2 which is neutral. On the other hand, calcium chloride is CaCl 2.

5 22. Chloride of lime is calcium hypochlorite [Ca(OCl) 2 ] which is alkaline. Calcium chloride is CaCl 2 which is neutral. On the other hand, calcium chloride is CaCl 2. When exposed to air, it loses its chlorine because it reacts with carbon dioxide present in air to give calcium carbonate and chlorine gas. CaOCl 2 + CO 2 CaCO 3 + Cl 2 Caclcium oxycholoride calcium carbonate chlorine gas 23. When gas is passed through a saturated solution of ammoniacal brine, ammonium chloride and sodium bicarbonate are formed. Compound 'Y' is used as antacid, hence compound 'Y' is sodium bicarbonate. Compound 'X' is ammonium chloride. Compound 'Y' decomposes to form another solid 'Z'. Compound 'Z' is sodium carbonate. The chemical equations for the reactions are as follows: Mob ALL THE BEST-- 5 / 12

6 24. When acids react with metal generally hydrogen gas is produced. Metal + Acid Salt + Hydrogen eg : Mg + 2HCl(dil) MgCl2 + H2 Pass this gas (H 2 ) through soap solution. The soap bubbles filled with the gas will rise up. If a burning splinter is brought near the gas, the bubble will burn with a 'pop' sound. 25. The gas that is evolved at anode during the electrolysis of brine is chlorine. Hence, G is chlorine. When chlorine gas is passed over dry slaked lime -, it produces bleaching powder which is used for disinfecting drinking water. Hence, Y is slaked lime (calcium hydroxide) and Z is calcium oxy-chloride (bleaching powder). Since Y and Z are calcium salts, therefore X is also a calcium salt. Since, X is a metal carbonate, it is calcium carbonate. Carbonates react with acids to produce carbon dioxide gas which when through a solution of slaked lime (Y) forms insoluble calcium carbonate. X Y Calcium carbonate Slaked lime (Calcium hydroxide) Mob ALL THE BEST-- 6 / 12

7 G Chlorine Z Calcium oxy-chloride (Bleaching powder) 26. Plaster of Paris is obtained by heating gypsum, CaSO 4.2H 2 O at 373 K. 2 CaSO 4.2H 2 O (CaSO 4 ).H 2 O + 3 H 2 O Gypsum Plaster of Paris The setting of Plaster of Paris is due to its hydration into gypsum. when mixed with water, it forms a paste which sets into a hard mass. (CaSO 4 ) 2.H 2 O Plaster of Paris + 3H 2 O 2CaSO 4.2H 2 O Gypsum 27. Some of the metal oxides dissolve in water to form alkalis. Since the oxide of metal M was soluble in water, it must have dissolved in water and formed an alkali (metal hydroxide). When a blue litmus strip was dipped in the solution, it did not go any change in colour. This indicates that the solution of metal oxide (MO) must be basic in nature. Therefore, the nature of the oxide of metal is basic. 28. A message or stimulus from receptor is relayed by sensory nerve to the spinal cord. It sends response through motor nerve to effectors for necessary action. This pathway of refex action is called as reflex arc. 29. Tropic movements 1. It can be easily observed in stems and roots. Nastic movements 1. It is clearly observed in bilaterally symmetrical organs such as leaves and petals of flowers. 2. It is due to unilateral stimulus which causes 2. The movements occur due to stimulus Mob ALL THE BEST-- 7 / 12

8 unequal growth on the two sides of a of light and temperature. stem, root and tendril. 3. Movement is related to stimulus, i.e., plant organs either move towards source of stimulus or away from it. Stimuli which causes movements in plants are gravity, light, touch, water and chemical substances. 4. Example: Bending of root towards gravity and shoot towards light. 3. Opening and closing of flowers of evening primrose and tobacco at the night and day respectively. This is due to unequal growth. 4. Example: Leaves of touch-me-not plant bend and droop on touching. 30. Hormones are chemical substances which are secreted in very less amount by specialized tissues called endocrine glands. Characteristics of hormones are- 1) They are required in very less amount. 2) Hormones are specific in their function. 3) They act away from the site of production. 4) Deficiency or over secretions of hormones have negative effects in the body. 31. (i) Oestrogen (ii) Growth hormone (iii) Insulin (iv) Thyroxin 32. Control and co-ordination in plants: Plants lack well organized control mechanism as in animals. However plants respond to light, touch and gravitational forces. Moreover growth and movements in plants are regulated by external and internal factors. Growth regulators: Plant growth regulators or phytohormones are the chemicals occurring in minute quantities and responsible for regulating metabolism, growth and development. The important phytohormones are Auxins (Indole-acetic acid). Gibberellins, Cytokinins, Ethylene, and Abscisic acid (ABA). All growth processes are regulated by Mob ALL THE BEST-- 8 / 12

9 one or photohormones acting synergistically or antagonistically. Section C 33. The following table gives the formulae of the given salts, and the acids and bases from which these salts may be obtained: S.No. Salts Formula Family Acid and B 1. Potassium sulphate K 2 SO 4 Potassium salts H 2 SO 4 and KOH 2. Sodium sulphate Na 2 SO 4 Sodium salts H 2 SO 4 and NaOH 3. Calcium sulphate CaSO 4 Calcium salts H 2 SO 4 and Ca(O 4. Magnesium sulphate MgSO 4 Magnesium salts H 2 SO 4 and Mg(O 5. Copper sulphate CuSO 4 Copper salts H 2 SO 4 and Cu(O 6. Sodium chloride NaCl Chloride salts HCl and NaOH 7. Sodium nitrate NaNO 3 Nitrate salts HNO 3 and NaOH 8. Sodium carbonate Na 2 CO 3 Carbonate salts H 2 CO 3 and NaO 9. Ammonium chloride NH 4 Cl Chloride salts HCl and NH 4 OH OR Compound 'A' is sodium hydrogen carbonate -. Sodium hydrogen carbonate or baking soda is a mild base. The reasons for its various uses are as follows:- (i) Sodium hydrogen carbonate is used in fire extinguishers because it produces gas on reaction with an acid. Carbon dioxide gas forms a blanket over the fire and cuts off the supply of air to the burning substance and the fire stops. (ii) It is used as an antacid because it neutralises excess acid ( ) present in stomach. It provides relief from acidity. (iii) It is an ingredient of baking powder. It is used in making bakery items because on Mob ALL THE BEST-- 9 / 12

10 reaction with an acid, it produces gas which makes bread, cakes, etc. soft and spongy. 34. Neuron or nerve cell is a structural and functional unit of the nervous system that is specialised to receive, conduct and transmit nerve impulses. A neuron (nerve cell) has three components: (i) Cell body (cyton) (ii) Dendrites (iii) Axon Functions: The information acquired at the end of the dendritic tip of a neuron sets off a chemical reaction which creates an electrical impulse. This impulse travels from die dendrite to the cyton along the axon of its end. At the end of axon, the electrical impulse sets off the release of some chemicals, which cross the synapse and start a similar electrical impulse in a dendrite of the next neuron. In this way nerve impulses travel in the body, from one neuron to another till it reaches the brain or the target organ. Thus, a nervous tissue is made up of an organised network of nerve cells or neurons which are specialised in conducting information via electrical impulse from one part of the body to another. OR Experiment to demonstrate hydrotropism. Mob ALL THE BEST / 12

11 1) Take a porous pot and fill it with water. 2) Keep a few freshly germinated pea seedlings in a dried sand. 3) As the water is not available in sand the root growing will bend towards porous pot filled with water. 4) You will observe a hydrotropic curvature of the root as it grows towards water. 5) This bending of root show the movement as a response towards water. 35. (a) An aqueous solution of an acid conducts electricity because in water an acid (HCl) dissociates to give ions. Since the current is carried out by the movement of ions, an aqueous solution of acid conducts electricity. (b) During dilution, more of acid dissociates into ions. Thus concentration of [H 3 O] + ions will increase on dilution. (c) Even on increasing [H 3 O] + ions, the number of ions per unit volume decreases. Therefore ph will increases on dilution. (d) (i) CO 2 gas will evolves accompanied by brick effervescence. (ii) H 2 gas will evolves accompanied by brick effervescence OR Experiment to demonstrate hydrotropism. Mob ALL THE BEST / 12

12 1) Take a porous pot and fill it with water. 2) Keep a few freshly germinated pea seedlings in a dried sand. 3) As the water is not available in sand the root growing will bend towards porous pot filled with water. 4) You will observe a hydrotropic curvature of the root as it grows towards water. 5) This bending of root show the movement as a response towards water. Mob ALL THE BEST / 12

Page 1 of 14. Website: Mobile:

Page 1 of 14. Website: Mobile: Question 1: You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red