Equal lengths of magnesium ribbons are t | Class 10 Science Chapter Acids, Bases and Salts, Acids, Bases and Salts 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?

Draw a schematic diagram of a circuit consisting of a battery of three cells of 2 V each, a 5 Ω resistor, an 8 Ω resistor, and a 12 Ω resistor, and a plug key, all connected in series.

Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.

Why are we looking at alternate sources of energy?

Name two safety measures commonly used in electric circuits and appliances.

What are reflex actions? Give two examples. Explain a reflex arc.

How does the embryo get nourishment inside the mother’s body?

What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

What are homologous structures? Give an example. Is it necessary that homologous structures always have a common ancestor?

The brain is responsible for

(a) thinking.
(b) regulating the heart beat.
(c) balancing the body.
(d) all of the above.

What are the qualities of an ideal source of energy?