# Important 5 Marks Questions for CBSE 10th Science Exam

Q 1:

Why are certain compounds called hydrocarbons? Write the general formula for the homologous series of alkanes, alkenes and alkynes and also draw the structure of the first member of each series. Write the name of the reaction that converts alkenes into alkanes, and also write a chemical equation to show the necessary conditions for the reaction to occur.

Q 2:

(a) Write the functions of each of the following parts in a human female reproductive system :

(i) Ovary

(ii) Uterus

(iii) Fallopian tube

(b) Write the structure and functions of the placenta in a human female.

Q 3:

With the help of one example for each, distinguish between the acquired traits and the inherited traits. Why are the traits/experiences acquired during the entire lifetime of an individual not inherited in the next generation? Explain the reason for this fact with an example.

Q 4:

Analyse the following observation table showing the variation of image distance (v) with object distance (u) in the case of a convex lens and answer the questions that follow without doing any calculations

(a) What is the focal length of the convex lens? Give a reason to justify your answer.

(b) Write the serial number of the observation, which is not correct. On what basis have you arrived at this conclusion?

(c) Select an appropriate scale and draw a ray diagram for the observation at S.No.2. Also, find the approximate value of magnification.

Q 5:

(a) If the image formed by a mirror for all positions of the object placed in front of it is always diminished, erect and virtual, state the type of the mirror and also draw a ray diagram to justify your answer. Write one use such mirrors are put to and why.

(b) Define the radius of curvature of spherical mirrors. Find the nature and focal length of a spherical mirror whose radius of curvature is + 24 cm.

Q 6:

(a) A student suffering from myopia is not able to see distinctly the objects placed beyond 5 m. List two possible reasons due to which this defect of vision may have arisen. With the help of ray diagrams, explain

(i) why the student is unable to see distinctly the objects placed beyond 5 m from his eyes?

(ii) the type of the corrective lens used to restore proper vision and how this defect is corrected by the use of this lens.

(b) If, in this case, the numerical value of the focal length of the corrective lens is 5 m, find the power of the lens as per the new Cartesian sign convention.

Q 7:

(a) Write the functions of each of the following parts in a human female reproductive system :

(i) Ovary

(ii) Uterus

(iii) Fallopian tube

(b) Write the structure and functions of the placenta in a human female

Q 8:

(a) If the image formed by a mirror for all positions of the object placed in front of it is always diminished, erect and virtual, state the type of the mirror and also draw a ray diagram to justify your answer. Write one use such mirrors are put to and why.

(b) Define the radius of curvature of spherical mirrors. Find the nature and focal length of a spherical mirror whose radius of curvature is + 24 cm.

Q 9:

Analyse the following observation table showing the variation of image distance (v) with object distance (u) in the case of a convex lens and answer the questions that follow without doing any calculations :

(a) What is the focal length of the convex lens? Give a reason to justify your answer.

(b) Write the serial number of the observation, which is not correct. On what basis have you arrived at this conclusion?

(c) Select an appropriate scale and draw a ray diagram for the observation at S.No.2. Also, find the approximate value of magnification.

Q 10:

(a) A student suffering from myopia is not able to see distinctly the objects placed beyond 5 m. List two possible reasons due to which this defect of vision may have arisen. With the help of ray diagrams, explain

(i) why the student is unable to see distinctly the objects placed beyond 5 m from his eyes?

(ii) the type of the corrective lens used to restore proper vision and how this defect is corrected by the use of this lens.

(b) If, in this case, the numerical value of the focal length of the corrective lens is 5 m, find the power of the lens as per the new Cartesian sign convention.

Q 11:

A student focuses the image of a candle flame, placed at about 2 m from a convex lens of focal length 10 cm, on a screen. After that, he moves the flame gradually towards the lens and, each time focuses its image on the screen.

(A) In which direction does he move the lens to focus the flame on the screen?

(B) What happens to the size of the image of the flame formed on the screen?

(C) What difference is seen in the intensity (brightness) of the image of the flame on the screen?

(D) What is seen on the screen when the flame is very close (at about 5 cm) to the lens?

Q 12:

(a) If the image formed by a mirror for all positions of the object placed in front of it is always diminished, erect and virtual, state the type of the mirror and also draw a ray diagram to justify your answer. Write one use such mirrors are put to and why.

(b) Define the radius of curvature of spherical mirrors. Find the nature and focal length of a spherical mirror whose radius of curvature is + 24 cm.

Q 13:

(a) A student suffering from myopia is not able to see distinctly the objects placed beyond 5 m. List two possible reasons due to which this defect of vision may have arisen. With the help of ray diagrams, explain

(i) why the student is unable to see distinctly the objects placed beyond 5 m from his eyes?

(ii) the type of the corrective lens used to restore proper vision and how this defect is corrected by the use of this lens.

(b) If, in this case, the numerical value of the focal length of the corrective lens is 5 m, find the power of the lens as per the new Cartesian sign convention

Q 14:

(a) Write the functions of each of the following parts in a human female reproductive system :

(i) Ovary

(ii) Uterus

(iii) Fallopian tube

(b) Write the structure and functions of the placenta in a human female.

Q 15:

With the help of one example for each, distinguish between the acquired traits and the inherited traits. Why are the traits/experiences acquired during the entire lifetime of an individual not inherited in the next generation? Explain the reason for this fact with an example.