Metals and Non-Metals — Science STD 10 — Question

Which of the following is the valence shell for the elements of second period of the modern periodic table?

1. M shell.
2. K shell.
3. L shell.
4. N shell.

A student is testing water to know which is best for cleansing purposes with soaps. He would find that the cleansing action of soaps is best when he uses water obtained from.

Which of the following statements are correct regarding isomers?
I. Isomers have same structural formula.
II. Isomers have same molecular formula.
III. Isomers have same chemical properties.
IV. The compound C₃⁢H₈ has no isomers.

Which one of the following is non-crystalline or amorphous?

Ethane and ethene can be distinguished by:

Acetic acid smells like:

When sodium hydrogen carbonate is added to ethanoic acid a gas evolves.
Consider the following statements about the gas evolved?
A. It turns lime water milky.
B. It is evolved with a brisk effervescence.
C. It has a smell of burning sulphur.
D. It is also a by-product of respiration.
The correct statements are:

What kind of reaction is the burning of natural gas?

The molecular formulae of some organic compounds are given below. Which of these compounds contains an aldehyde group?

Which among the following is not a base?

1. NaOH.
2. KOH.
3. NH₄OH.
4. C2H₅OH.