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CBSE Class 10 Science Solved Question Paper 2018

Short Answer Type

Write the energy conversion that takes place in a hydropower plant.

A Mendelian experiment consisted of breeding pea plants bearing violet flowers with pea plants bearing white flowers. What will be the result in F₁ pregeny?

Name one gustatory receptor and one olfactory receptor present in human beings.

Write a and b in the given flow chart of a neuron through which information travels as an electrical impulse.

$[\begin{matrix} D e n r i t e \end{matrix}] \overset{}{\to} [\begin{matrix} a \end{matrix}] \overset{}{\to} [\begin{matrix} b \end{matrix}] \overset{}{\to} [\begin{matrix} E n d P o i n t o f N e w r o n \end{matrix}]$

If the image formed by a spherical mirror for all positions of the object placed in front of it is always erect and diminished, what type of mirror is it? Draw a labelled ray diagram to support your answer.

A compound ‘X’ on heating with excess conc. sulphuric acid at 443 K gives an unsaturated compound ‘Y’. ‘X’ also reacts with sodium metal to evolve a colourless gas ‘Z’. Identify ‘X’, ‘Y’ and ‘Z’. Write the equation of the chemical reaction of formation of ‘Y’ and also Write the role of sulphuric acid in the reaction.

7.
State the laws of refraction of light. Explain the term ‘absolute refractive index of a medium’ and write an expression to relate it with the speed of light in vacuum.

(1) The incident ray, the refracted ray and the normal to the interface of two media at the point of incidence all lie in the same plane.

(2) For the light of a given colour and for a given pair of media, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant.

This is also known as Snell's Law.

Mathematically it can be written as:

$\frac{\sin i}{\sin r} = c o n s \tan t =^{A} μ_{B}$

Here, μ is the refractive index of medium B with respect to medium A.

Refractive index of a medium with respect to the vacuum is known as the absolute refractive index.

What is meant by the power of a lens? Write its SI unit. A student uses a lens of focal length of 40 cm and another of –20 cm. Write the nature and power of each lens.

Write one main difference between asexual and sexual mode of reproduction. Which species is likely to have comparatively better chances of survival - the one reproducing asexually or the one reproducing sexually ? Give a reason to justify your answer.