What is the role of the brain in reflex | Class 10 Science Chapter Control and Coordination, Control and Coordination 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?

Name the sodium compound which is used for softening hard water.

Why is there a need to harness non-conventional sources of energy? Give two main reasons.

Evolution has exhibited a greater stability of molecular structure when compared with morphological structures. Comment on the statement and justify your opinion.

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

Why does bread mould grow profusely on a moist slice of bread rather than on a dry slice of bread?

How would these advantages differ from the advantages of using a long-term perspective in managing our resources?

No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be

(a) only plane.
(b) only concave.
(c) only convex.
(d) either plane or convex.

Describe the structure and functioning of nephrons.

What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?

What are the environmental consequences of the increasing demand for energy? What steps would you suggest to reduce energy consumption?