CBSE Class X – Science Chemistry Exam (Full Syllabus)

Inert gases like helium or nitrogen both can be used for the storage of fresh sample of oil for a long time, as they do not react with most elements, including oxygen

When FeSO4 is heated strong, it decomposes to form a brown solid ferric oxide, sulphur dioxide and sulphur trioxide

When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of copper sulphide is obtained and the sulphuric acid. So formed remains in the solution.

Chemical reaction in beakers A and B gives out heat. Hence, the temperature of the solution increases. Thus, we can call it an exothermic reaction._x000D_In beaker C, heat is absorbed from water instead and hence, the temperature decreases. Thus, we can call it an endothermic process.

The increasing order of acid strength is water < acetic acid < hydrochloride acid. Hydrochloride acid is a strong acid and ionises fully in water.

Clove oil is an olfactory indicator. These the substances which give one type of odour in acidic medium and a diferent odour in basic medium so a visually challenged student favours to use clove oil as an acid-base indicator.

If 10 ml of H₂SO₄ is mixed with 10 ml of Mg(OH)₂ of the same concentration, the result solution be MgSO₄ which is a neutral salt and universal indicator will give the green colour in this solution

Baking powder is a mixture of sodium hydrogen carbonate and tartaric acid NaHCO₃ + H+ → CO₂ + H₂O + Sodium salt (from tartaric acid) of acid Carbon dioxide (CO₂) produced during reaction can cause bread or cake to rise and makes Baking powder, tartaric acid neutralises the salt and cake does not taste bitter.

Lime (CaO) is the base that reacts with a dilute acid such as HCl to form a salt called calcium chloride.

Second period contains elements with atomic number 3(Li), Ǫ(N) and 10(Ne). This period also contains the elements beryllium, boron, carbon, oxygen and fuorine

The elements boron (B), silicon (Si) and germanium (Ge) exhibit intermediate properties of metals and non-metals, therefore, they are called as metalloids

Carbon always forms covalent compounds by sharing its electrons with other at atoms.The two electrons shared by the atoms are attracted to the nucleus of both the atoms.

The major constituent of the liquefied petroleum gas is butane.

Catenation is the property of self-linking of an element by which an atom combines with the other atoms of the same element to form long chains

As the compound, CH₃CH₂CH=CH₂ contains four carbon atoms and a double bond attached to the first carbon, so the I.U.P.A.C name of CH₃CH₂CH=CH₂ is But-1-ene.

Prolong heating of red hot iron with steam forms Fe₃O₄ with hydrogen gas.

Aqua-regia is the mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3:1. Aqua-regia, being a strong acid, dissolves gold.