Carbon and its Compounds — Science STD 10 — Question

According to Mendele′ ev's Periodic Law, the elements were arranged in the periodic table in the order of:

1. Increasing atomic number.
2. Decreasing atomic number.
3. Increasing atomic masses.
4. Decreasing atomic masses.

Juice of tamarind turns blue litmus to red. It is because of the presence of an acid called:

The chemical equations are balanced to satisfy one of the following laws in chemical reactions. This law is know as:

A student puts a drop of reaction mixture of a personification reaction first on a blue litmus paper and then on a red litmus paper. He may observe that:

Write the balanced equation for the reaction for the following statement:
Mg burns in presence of air.

The two metals which can be extracted just by heating their sulphides in air are:

The daffodil plants grow best in a soil having a pH range of 6.0 to 6.5. If the soil in a garden has a pH of 4.5, which substance needs to be added to the soil in order to grow daffodils?

In an attempt to demonstrate electrical conductivity through an electrolyte, the following apparatus figure, was set up. Which among the following statement(s) is (are) correct?

1. Bulb will not glow because electrolyte is not acidic.
2. Bulb will glow because NaOH is a strong base and furnishes ions for conduction.
3. Bulb will not glow because circuit is incomplete.
4. Bulb will not glow because it depends upon the type of electrolytic solution.

1. 1 and 3
2. 2 and 4
3. 2 only
4. 4 only

During hydrogenation of oil, the catalyst commonly used is: