Our Environment — Science STD 10 — Question

While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?

Name the reagent which is able to dissolve gold and platinum.

A gas is evolved when ethanol reacts with sodium. Name the gas evolved and also write the balanced chemical equation of the reaction involved.

What is yeast? Describe the process of reproduction in yeast with the help of labelled diagrams.

An element A has an atomic number of 6. Another element B has 17 electrons in its one neutral atom.

1. N which groups of the periodic table would you expect to find these elements?
2. What type of bond is formed between A and B?
3. Suggest a formula of the compound formed between A and B.

State any two properties of magnatic field lines.

A person can comfortably read a book but finds it difficult to read the number on a bus parked 5 m away from him. Name the type of defect of vision he is suffering
from. Which type of lens should be used in his spectacles to correct his vision?

The elements A, B and C belong to groups 1, 14 and 17 respectively of the periodic table.

1. Which two elements will form a covalent compound?
2. Which two elements will form an ionic compound?

What are fossil fuels? Give three examples of fossil fuels.

Choose the one term from the following which differs from the other three. Broccoli, wild cabbage, Cauliflower, and Kale.