Chemical Reactions and Equations — Science STD 10 — Question

Define a homologous series. Give the name and structural formula of one homologue of the following:
CH₃OH

Why should curd and sour substances not be kept in brass and copper vessels?

When the powder of a common metal is heated in an open china dish, its colour turns black. However, when hydrogen is passed over the hot black substance so formed, it regains its original colour. Based on the above information answer the following questions:

1. What type of chemical reaction takes place in each of the two given steps?
2. Name the metal initially taken in the powder form. Write balanced chemical equations for both reactions.

Potatoes grow well on Anhad’s farm which has soil with a pH of 5.5. Anhad decides to add lot of lime to soil so that he can grow broccoli in the same farm:

1. Do potatoes grow better in acidic or alkaline soil?
2. Does broccoli grow better in acidic or alkaline soil?

State the law of conservation of mass.

Draw the structures for the following compounds:

1. Ethanal.
2. Propanal.
3. Butanal.
4. Pentanal.

In Mendeleev’s periodic table, why was there no mention of noble gases like helium, neon and argon?

How could the person change his eating habits to lessen chances of suffering from tooth decay?

The pH values of six solutions A to F are given below:
A = 0, B = 11, C = 6, D = 3, E = 13, F = 8

What happens when an acid reacts with a metal? Give chemical equation of the reaction involved.