The magnification produced by a plane mi | Class 10 Science Chapter Light - Reflection and Refraction, Light - Reflection and Refraction 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?

Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents such as ethanol also?

In tobacco plant, the male gametes have twenty four chromosomes.
What is the number of chromosomes in the female gamete?
What is the number of chromosomes in the zygote?

What are various ways to avoid pregnancy? Elaborate any one method.

Explain the importance of soil for plant growth.

Why does menstruation occur?

Explain the mechanism of the cleaning action of soaps.

What are the problems caused by the non-biodegradable wastes that we generate?

Why is improper disposal of waste a curse to the environment?

Can you consider cell division as a type of reproduction in unicellular organism? Give one reason.

Describe sexually transmitted diseases and mention the ways to prevent them.