The Human Eyes And The Colourful World — Science STD 10 — Question

What are hydrocarbons? Give one example.

What is the common name of propanone?

Keeping the resistance constant, the potential difference applied across the ends of a component is halved. By how much does the current change?

Which phenomenon makes us see the sun:

1. A few minutes before actual sunrise?
2. A few minutes after actual sunset?

What is the usual number of valence electrons and valency of group 18 elements of the periodic table?

What is the long fibre of a neuron known as?

Which type of circuit, series or parallel, is preferred while connecting a large number of bulbs:

1. For decorating a hotel building from outside?
2. For lighting inside the rooms of the hotel?

What effect does the concentration of H ions have on the nature of a solution?

Translate the following statements into chemical equations and then balance the equations:
Carbon disulphide burns in air to give carbon dioxide and sulphur dioxide.

In dispersion of sunlight by a glass prism, which colour is deviated the least?