SCIENCE
Class-X
Part-A
1. Choose the right option in the following questions
I. Which of the following statement about the reaction below are incorrect
2pb0(s)+c(s) ————-> 2pb(s)+co2(G)
(a) led is getting reduced
(b) carbon dioxide is getting oxidised
(C) carbon is getting oxidised
(D) lead oxide is getting reduced
(i) (a) and (b) (ii) (a) and (c)
(iii) (a),(b) ans (c) (iv) All
Ans : (i) (a) and (b)
2.. A Solution turns red litmus blue its pH is likely to be:
(a) 1
(b) 4
( c) 5
(d) 10
Ans (d) 10
3. A Solution reacts with crushed egg shells to give a gas that turns lime water milky. a solution contains:
(a) NaCI
(b) HCI
( c) LiCI
(d) KCI
Ans: (b) HCI
4. Food cans are coated with Tin and not with zinc because:
(a) zinc is costlier than tin
(b) zinc has a higher melting point than tin
(c) zinc is more reactive than Tin
(d) zinc is less reactive than Tin
Ans: ( c) Zinc is more reactive than tin.
5. Butanone is a four carbon compound with the functional group:
(a) Carboxylic acid
(b) Aldehyde
(C) Ketone
(d) alcohol
Ans: ( c) Ketone
6. Which of the following statement is not a correct statement about the trend when going from left to right across the periods of periodic table:
(a) The elements became less metallic in nature
(b) The number of Valence Electrons increases
(c) the atoms lose their electrons more easily
(d) the oxidized become more acidic
Ans: ( c) The atoms lose their electrons more easily
7. The Kidneys in human beings are a part of the system for:
(a) Nutrition
(b) Respiration
(c) Excertion
(d) transportation
Ans : ( c ) Excretion
8.The autotrophic mode of nutrition requires:
(a) carbon dioxide and water
(b) Chlorophyll
(c) Sunlight
(d) all of the above
Ans:(d) all of the above
9. Which of the following is a plant hormone:
(a) Insulin
(b)Thyroxine
(c) Oestrogen
(d) Cytokinin
Ans: (d) Cytokini
10. An example of homologous organ is:
(a) Arrow and a dog’s fore-leg
(b) teeth and an elephant’s tusk
(c) potato and runner of grass
(d) all of the above
Ans: (d) all of the above
11. in Revolutionary term we have more in common with
(a) a Chinese school boy
(b) Chimpanzee
(c) Spider
(d) a bacterium
Ans: (a) A Chinese school boy
12. Where an object should be placed in front of a convex lens to get a real image of the size of the object?
(a) at the principal focus of the lens
(b) at twice the focal length
(c) at infinity
(d) e between the optical centre of the lens and its principal focus
Ans: (b) At twice the focal length
13. no matter how far you stand from a mirror your image appears erect the mirror is likely to be
(a) only plane
(b) only concave
(c) only convex
(d) either plane or convex
Ans: (d) either plane or convex
14. the solar water heater cannot be used to get hot water on:
(a) a sunny day
(b) a cloudy day
(c) a hot day
(a) a windy day
Ans: (b) a cloudy day
15. which of the following country is known as the country of winds:
(a) Denmark
(b) Russia
(c) America
(d) China
Ans: (a) Denmark
16.Which of the following constitutes a food chain:
(a) grass, wheat and mango
(b) grass, good and human
(c) goat, coward elephant
(d) grass, fish and goat
Ans: (b) grass, good and human
17.Big Ganga runs its course of how many kilometre from Gangotri in the Himalayas to Ganga sagar in the Bay of Bengal:
(a) 1500km
(b) 2500 km
(c) 3500 km
(d) 4500 km
Ans: (b) 2500 km
PART-B
18.A solution of a substance X is used for whitewashing
(i) Name the substance X and write its formula
(ii) write the reaction of substance X with water
Ans: (i) Which substance X is quicklime. its chemical name is calcium oxide and its formula is CaO.
(ii) CaO(s) + H2O (i)–> ca(OH)2 (aq)
19.Plaster of paris should be stored in moisture proof container explain why?
Ans. plaster of paris should be stored in moisture proof container because it can get hardened by reacting with moisture/ water in other words we can say that it will set and get spoilt, so it should be stored in the master free container.
20.What are the two properties of Carbon which lead to the huge number of carbon compound we can see around us?
Ans. b two properties of Carbon which lead to the huge number of carbon compound we can see around us are
(i) Tetravalency (ii) Catenation
21.What were the limitation of newlands law of octaves?
Ans. Limitation of newlands law of octaves were:
(a)The law was applicable only up to calcium. after calcium every eighth element did not possess properties similar to that of the first.
(b) new land assume that only 56 elements exist in nature. but later several new elements were discovered which did not fit into the law of octaves.
(c) newland arrested two element into the same slot and put some and like elements under the same not eg Co and Ni were placed with F,CI,Br
(d)Law of octaves could not work well with the heavier elements
22. How do we detect the smell of an Agarbatti (incense stick) .
Ans.The Chemicals from agarbatti diffused into the ear and reach our nose. when we inhale through nostrils these Chemicals enter into the nasal cavity. there they get it is all on the the moiste surface nasl epithelium. the olfactory receptors receives the chemical stimulus and colour it on the brain, where the stimulus is analysed and felt. so, we feel the incense.
23. explain the term analogous and homologous organ with examples?
Ans. Analogous organs:The organs which perform similar function and looks similar but are different in their origin and structure are called analogous organs.
Examples:-
(a)The wings of insect and birds.
(b) Wings of bats and insects
(c) The tendril s of Bengal gram/pea.
(d) Tendrils of grape wine.
Homologous organs: The organs which are similar in origin and structure but may or may not differ in their functions.
Exampls:-
(a) Wings of bird and fore- legs of horse
(b) arms of human and fore- legs of cows
(c) fore- legs of frog and wings of birds
24.Videos of curvature of a spherical mirror is 20 cm what is its focal length?
Ans R=20 cm,f =?
R=2f or R = f
2
Focal Length (f) =20=10cm
2
25.Why does the sun appear reddish early in the morning?
Ans. light from the sun near the origin passes through the thick layer of air. it covers large distance in the earth’s atmosphere before reaching our eyes.
Near the origin, most of the blue light of shorter wavelength are scattered away by the particles. therefore, the that eyes is greater wavelength. this gives rise to the reddish appearance of the Sun.
26. list the properties of magnetic lines of force?
Ans properties of magnetic lines of force are:
(a) these emerge from north pole and merge at the South Pole
(b) the direction of field line is from its south pole to its North Pole.
(c) the magnetic field lines are closed curves
(d) the relative strength of the magnetic field is shown by the degree of closeness of the field line
(e) no two field lines are found to cross each other.
27 can any source of energy be pollution free? Why or why not?
Ans. No, Any source of energy cannot be totally pollution free. e some sources cause pollution during their production and sound source causes pollution at the time of their manufacturing. for example, Solar cells known as pollution free source of energy but during their manufacturing causes pollution which damage the atmosphere.
28. what are the disadvantages of fossil fuels?
Ans. disadvantages of fossil fuels are given below.
(a) fossil fuels are present in Limited supply and these will exhaust soon.
(b) fossil fuels on combustion produce lot of harmful gases which causes air pollution.
(c) excess use of fossil fuel is releasing lot of Co2 into the atmosphere which is the main cause of greenhouse effect and global warming.
(d) gases like SO2 and so3 and NO2 produced due to the burning of fossil fuels causes acid rain.
29. What can you as an individual do to reduce your consumption of the various natural resources.
Ans. we can reduce the consumption of various natural resources:
(a) by using minimum quantity of electricity
(b) By during 5R’s rule Al
(c) we should not waste the food
(d) we should stop the wastage of water
(e) we should use a gas instead of wood for cooking food
PART-C
30. Why does the colour of copper sulphate solution change when an iron nail is dipped in it?
Ans: when copper sulphate solution reacts with iron, then following reaction take place:
CuSO4 (aq) + Fe (s) ——-> FeSo4(aq) + Cu(s)
Copper Sulphate Iron Ferrous Sulphate Copper
Copper sulphate solution is blue in colour. iron being more reactive than copper, displaces copper from its salt solution. so, the blue colour fades away due to formation of ferrous sulphate which is light green in colour.
31. what is your role of acid in our stomach?
Ans. Gastric juice secreted from stomach contain hydrochloric acid HCG who is the pH is a nearly 2.0 it perform the following functions:
(a)Provide se acidic medium for enzymes to active, help in conversion of pepsinogen which is positive form.
(b)Kid kills microbes present in food.
(c) it too soft and the food
32 why does the sky appear dark instead of blue to an astronaut?
Ans. there is no atmosphere for the astronaut who are flying at such high. the sky appears dark to passengers flying at very high altitude, as scattering is not prominent at such Heights
34. why why is the damage of the Ozone Layer a cause for concern? what steps are being taken to limit the damage?
Ans. damage to Ozone near is cause of concern because it will allow ultraviolet radiation to react to earth surface which can cause following problems:
(a) skin cancer
(b) Cataract
(c) immune system disorder
(d) death of microbes
(e) lowering for pricing of agriculture production
(f) cause ecological imbalance
following steps are being taken to limit the damage caused by ozone depletion:
(a) in 1987 UNCEP for the agreement to freeze CFCS Protection Act 1986 levels
(b)Reproduction and use of ozone depleting substances(ODS) has been reduced significantly
36. What were the criteria used by Mendeleev in creating his periodic table?
Ans. we create area used by Mendeleev in creating his periodic table are given below:
(a) the properties of element are the periodic function of their atomic masses i.e the elements are arranged in increasing order of their atomic masses
(b) similarity in physical and chemical properties were also considered
(c)the formula of the hydride and oxide is formed by an element where it treated as one of the basic property of an element for its classification
37. why is the use of iodised salt advisable?
Ans. we are utilised common salt contain salt of Iodine, fluidyne is required for synthesis of of thyroxine hormone in the thyroid gland. aur ok sign is vital organ which contain carbohydrates, fats and protein metabolism. deficiency of their organ leads to Goitre disease. deficiency of iodine in children leads to poor physical and mental development
PART-D
38. What is Ohm’s law? How can it be verified?
Ans: Ohm’s law:It is stated that the current passing through a conductor is directly proportional to the potential difference across its and provided the temperature and other physical condition remain unchanged.
where R is a constant of proportionality called resistance.
experimental verification of Ohm’s Law: collector an a meter, battery, key and rheistat as shown in figure. football club in the key K. read the values of potential difference across a resistor R with the help of voltmeter V and the current flowing through the resistor with the help of ammeter.
Note the readings. very the current in the circuit by sliding contact of rheostat and go on nothing reading in voltmeter and ammeter.
find the ratio of voltmeter reading and corresponding ammeter reading in each case. you will find the ratio remain same in each case. this proves Ohm’s law.
39.Write three difference between sexual and asexual reproduction?
Ans: Difference is between sexual and asexual reproduction:
40.What are contraceptive methods? explain any two.
Ans: different methods of contraceptive of:
(a)Mechanical barriers
(b) chemical methods
(c) surgical methods
(d) intrauterine contraceptive devices.
(a) Mechanical barriers:
(i) Also use condoms to prevent entry of sperm into the the vagina
(ii) female uses cervical cap to prevent entry of sperm into uterus and fallopian tubes
Female condoms are also available in the market but are not much popular because of lack of awareness and poor economic conditions
(b) chemical methods: Two types of cells are used by women:
(i) coronavirus: oral pills contain hormones which prevent release of egg from the ovaries eg Mala-D,Saheli.
(ii) vaginal pills: these contain chemical which can kill the sperms so they are spermicides.