CBSE Class 10 Science Question Papers 2019

CBSE Class 10 Science Question Papers 2019 - You will find here Solved Question Papers of Central Board of Secondary Education (CBSE) Science (Theory & MCQ) for academic session 2019-20.


Theory

Which of the following statements is not applicable to compounds of carbon?
(1) They have low melting and boiling points
(2) They are ionic in nature
(3) They form a homologous series
(4) They are generally soluble in organic solvents

Which of the following statements regarding the properties of graphite is incorrect?
(1) It is a non-metallic substance
(2) It does not conduct electricity
(3) It is used as a lubricant
(4) It is soft and slippery in touch

Which of following is incorrect regarding bonding in carbon?
(1) It forms only covalent bonds
(2) It forms ionic as well as covalent bonds
(3) It can bond with other atoms of carbon to form long chains, branched chains and cyclic chain structures
(4) It shares all of its four valence e– for bonding to attain the noble gas configuration

Carbon forms _________ covalent bonds with other atoms owing to its ___________.
(1) Weak, small atomic size
(2) Strong, large atomic size
(3) Weak, large atomic size
(4) Strong, small atomic size

Which of the following does not show the property of catenation?
(1) C₂H₆ (2) C₂H₄
(3) CO₂ (4) C₂H₂

A female reproductive part, present at the centre of a flower is
(1) Sepals
(2) Petals
(3) Stamens
(4) Carpels

In bread mould (Rhizopus), asexual reproduction takes place through
(1) Budding
(2) Regeneration
(3) Spore formation
(4) Fragmentation

Which of the following occurs, if egg is not fertilised?(1) Ovulation
(2) Menarche
(3) Menopause
(4) Menstruation

The parasite causing Kala-azar, which reproduces by binary fission is(1) Trypanosoma
(2) Leishmania
(3) Noctiluca
(4) Plasmodium

In which of the following plants, unisexual flower is formed?(1) Papaya
(2) Hibiscus
(3) Mustard
(4) Pisum sativum

1. Why ethanol is used as a fuel?

2. Define accommodation in human eye.

3. Name a synthetic chemical which causes depletion of ozone layer.

4. The electronic configurations of three elements are given below:
X 2
Y 2, 6
Z 2, 8, 2
(i) Which element belongs to the second period of the periodic table?
(ii) Which element belongs to the eighteenth group of the periodic table?

5 Element X forms a chloride with the formula XCl2, which is a solid with a high melting point. Element X will belong to which group of the periodic table?

6. Write down the disadvantages of burning of fossil fuels.

7. How many isomers of the following hydrocarbons are possible?
(i) C3H8
(ii) C4H10
(iii) C5H12

8. Justify the statement “sexual reproduction is advantageous over asexual reproduction”.

9. What are fossils? How is the age of the fossils determined?

10. What is a monohybrid cross? Draw a Punnet square of a monohybrid cross and write the genotypic and phenotypic ratio obtained in the F2 generation of the monohybrid cross.

11. Find the magnification, if the object is placed at a distance of 20 cm in front of a concave mirror of focal length 40 cm.

12. Find the ratio of refractive indices of two media, if the speed of light in first and second medium is 2 × 108 m/s and 1 × 108 m/s respectively

13. The near point of an elderly person is 50 cm from the eyes. Find the focal length and power of the corrective lens he needs.

14. Write the structural formula of the following:
(i) Hexanal
(ii) Benzene

15. Explain soaps and detergents. Write down advantages and disadvantages of detergents over the soaps also write cleansing action of soaps and detergents.

16. Draw a labelled diagram of an angiospermic flower and germination of pollen on stigma.

17. An object is placed at a distance of 12 cm from a concave mirror of radius of curvature 16 cm. Find the position of the image.
(a) Find the position of the image.
(b) Is the image real or virtual?
(c) Find the size of the image.
(d) Is the image erect or inverted?

MCQ

Que. 1 Acetic acid was added to four test tubes containing the following chemicals:

 a. Sodium carbonate
b. Blue litmus solution
c. Lime water
d. Distilled water
Which amongst these is/ are correct option(s) for carrying out a characteristic test for identification of a carboxylic acid (acetic acid) in the laboratory?
1. (a) only
2. (c) only
3. (a) and (b)
4. (c) and (d)
Que. 2 On adding concentrated NaOH solution to a test tube containing phenolphthalein, the colour change observed by a student would be:
a. Pink to colourless
b. Pink to blue
c. Colourless to pink
d. Red to blue
Que. 3 A student observed a focussed slide of a stage of binary fission in Amoeba under a microscope as seen below:
SCIENCE
Which of the following is most appropriate statement with respect to the observation
a) preliminary stage
b) intermediate stage where the nucleus is divided and cytoplasm is not
c) intermediate stage where the cytoplasm is divided and nucleus is not
d) final stage
Que. 4 A student while observing the properties of acetic acid would report that this acid smells like
(i) vinegar and turns red litmus blue
(ii) rotten egg and turns red litmus blue
(iii) vinegar and turns blue litmus red
(iv) rotten egg and turns blue litmus red
VSA:-
Que. 5 Give one example of a unisexual flower.
Que. 6 Draw the electron dot structure of the gas molecule which is liberated when zinc metal is treated with aqueous NaOH solution.
Que. 7 Find the period and group of the element whose atomic number is 12.
Que. 8 Refractive index of two material medium X and Y are 1.3 and 1.5 respectively. In which of the two, the light would travel faster?
Que. 9 Write in one word or at the most in one sentence about the following
(i) Mirrors used by dentists to examine teeth
(ii) The smallest distance, at which the eye can see objects clearly without strain.
SA I:-
Que. 10 List two differences between acquired and inherited traits.
Que. 11 State how would you distinguish between Acetic acid and Ethanol in your laboratory. Give chemical equation of the reactions shown by them. Write the chemical equations involved.
Que. 12 Complete the reaction (s) given below and classify them as Combustion /Oxidation / Addition / Substitution reaction.
(i) CH3 CH2 CH2 OH alk.KMn04 →Heat
(ii) C2 H4 + H2 Ni catalyst
Que. 13 Explain why?
(i) ‘Danger’ signal are red in colour.
(ii) Convex mirrors are commonly used as rear – view mirrors.
Que. 14 Study the ray diagram given below and answer the following questions -
SCIENCE
(i) State the type of lens used in the figure.
(ii) List two properties of the image formed.
(iii) In which position of the object will the magnification be -1?
Que. 15 What is meant by power of accommodation of the eye? How is it related to the focal length of the eye lens?
SA II:-
Que. 16 “Fossils are related to evolution”, justify this statement. Give the two ways by which age of the fossils can be estimated?
Que. 17 ‘Variation is beneficial to the species but not necessarily for the individual”, give three reasons to justify it.
Que. 18 Two elements with symbol X (atomic no. 11) and Y (atomic no. 13) are placed in the III period of the modern periodic table -
(i) Which amongst the two has more metallic character?
(ii) Calculate the valency of each element.
(iii) Element ‘Y’ is smaller than ‘X’ in terms of atomic size. Is the statement true, justify?
LA:-
Que. 19
a) Identify the parts the 1, 2, 3 and 4 of the diagram given below.
b) List two changes that can be observed in the flower after fertilization.
SCIENCE
Que. 20 A 2.0 cm tall object is placed perpendicular to the principal axis of a concave lens of focal length 10 cm. The distance of the object from the mirror is 15 cm. Find the nature, position and size of the image formed. Represent the situation with the help of a ray diagram.