Select the mis-matched pair in the follo | Class 10 Science Chapter Our Environment, Our Environment NCERT Solutions

When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.

Outline a project which aims to find the dominant coat colour in dogs.

Draw the structure for the following compounds.                

       (i)    Ethanoic acid             (ii)   Bromopentane*
       (iii)  Butanone                   (iv)   Hexanal.

*Are structural isomers possible for bromopentane?

A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?

How is the sex of the child determined in human beings?

(a)  What property do all elements in the same column of the Periodic Table as boron have in common?
(b)  What property do all elements in the same column of the Periodic Table as fluorine have in common?

Calculate the number of electrons constituting one coulomb of charge.

A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?

What is an homologous series? Explain with an example.

Why is variation beneficial to the species but not necessarily for the individual?

Differentiate between inherited and acquired characters. Give one example for each type.

What is the difference between displacement and double displacement reactions? Write equations for these reactions.

Explain the refraction of light through a triangular glass prism using a labelled ray diagram. Hence define the angle of deviation.

What are the environmental consequences of using fossil fuels?
Suggest the steps to minimise the pollution caused by various sources of energy including non-conventional sources of energy.

What is the function of digestive enzymes?

Name the substance which on treatment with chlorine yields bleaching powder.

A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or away from the normal? Why?

Outline a project which aims to find the dominant coat colour in dogs.

Compare and contrast fossil fuels and the Sun as direct sources of energy.

What are the functions of gastric glands present in the wall of the stomach?