Life Processes — Science STD 10 — Question

Explain why, when air is taken in and let out during breathing, the lungs always contain a residual volume of air.

What is a detergent? Name one detergent.

State the advantages of constructing dams across the rivers.

How do unicellular organisms perform excretion?

Why does ethyne (acetylene) burn with a sooty flame?

The linear magnification produced by a spherical mirror is +3. Analyse this value and state the (i) type of mirror and (ii) position of the object with respect to the pole of the mirror. Draw ray diagram to show the formation of image in this case.

State the various characteristics of chemical reactions.

What is ‘Baking Powder’? How does it make the cake soft and spongy?

What are the two characteristics of a good source of energy?

InMendele′ ev’s Periodic Table the elements were arranged in the increasing order of their atomic masses. However, cobalt with atomic mass of 58.93amu was placed before nickel having an atomic mass of 58.71amu. Give reason for the same.