An electric heater of resistance 8 &Omeg | Class 10 Science Chapter Electricity, Electricity 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?

All the human races like Africans, Asians, Europeans, Americans and others might have evolved from a common ancestor. Provide a few evidences in support of this view.

Why do we apply paint on iron articles?

Why is there a need for harnessing non-conventional sources of energy? How can energy be harnessed from the sea in different ways?

What would be the ratio of chromosome number between an egg and its zygote? How is the sperm genetically different from the egg?

Is the position of a star as seen by us its true position? Justify your answer.

Why are the Arabari forests of Bengal known to be a good example of conserved forest?

Label the endocrine glands in Figure 7.3.

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

In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?

Compute the heat generated while transferring 96000 coulomb of charge in one hour through a potential difference of 50 V.