Explanation

Explanation

The molar mass of CaCO₃ is approximately 100 g/mol.

The molar mass of calcium (Ca) in CaCO₃ is about 40 g/mol.

The proportion of calcium in CaCO₃ is  40/ 100 = 0.4

Therefore, in 0.1 g of CaCO₃, the amount of calcium is  0.1×0.4=0.04 g.

Explanation

• A chemical formula tells us the number of atoms of each element in a compound.
• It contains the symbols of atoms of the elements present in the compound.
• As well as how many there are for each element, in the form of subscripts.

Explanation

Filtration by a glass funnel and filter paper is very time-consuming.

Filtration using traditional tools like a glass funnel and filter paper is a slow process because:

Liquid passes through the filter gradually

Solids take time to separate completely

So, it takes a lot of time, which is what "time-consuming" means.

Explanation

In the number 8.70 × 10⁻¹²:

All non-zero digits and zeros between or after non-zero digits (if decimal is present) are significant.

So, 8, 7, and the 0 after 7 are all significant.

Therefore, the number has 3 significant figures.

Explanation

If the maximum value of the principal quantum number (n) for an atom is 4, the total number of electrons in that atom is 32.

This is because the maximum number of electrons in a shell is given by 2n², and for n=4, this calculation results in 2 * 4² = 32. 

Explanation

When hydrogen loses its electron, it forms H⁺, similar to alkali metals (like Na⁺, K⁺) that also form +1 ions.

Due to this behavior, hydrogen is often placed in Group 1 (alkali metals) in the periodic table.

Explanation

Lead (Pb) belongs to Group IVA (Group 14) of the periodic table, along with carbon, silicon, and tin.

Elements in this group have 4 valence electrons and show a mix of metallic and non-metallic properties.

Explanation

• H2 is only a homo atomic [homo: same] molecule.
• Rest three are hetero atomic [hetero: different] molecules).

Explanation

 Cs (Cesium), Rb (Rubidium), and K (Potassium) are all alkali metals that can form superoxides when heated in excess oxygen.