CBSE Class X – Science Chemistry Exam (Full Syllabus)

Decomposition reaction can be defined as the reaction which involves decomposition of one compound to more than one substance. Endothermic reactions require heat energy to form products.

Acids turn blue litmus solution to red. They have a sour taste as in the case of vinegar and are sticky to touch. On the other hand, bases turn red litmus solution to blue. Bases are bitter in taste as in the case of baking soda and are slippery to touch.

Common salt (NaCl) is formed after a reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH)

When the pH of an aqueous solution is higher, its acidic properties are weak. Thus, it is a base. When the pH an aqueous solution is lower, its basic properties are weak. Thus, it is an acid.

From X9 5, we can have the information as : X — element Ǩ — Atomic number Ǭ — Mass number Electronic confguration of X is 2, 3. Group number is found out on the basis of valance electrons. Valence electrons are 3 so group number is 10 + 3 = 13. Period can be found out by knowing the number of shells

Germanium element found a place in the periodic table later in the place of Eka–silicon in Mendeleev’s periodic table.

Atomic number 14 (electronic confguration of 2,8,4) is for silicon element, which is a metalloid and exhibit properties of both metal and non-metal

Eka-aluminum (later identified as gallium) has a valency of 3. Hence, the oxide would be of the molecular formula E₂O₃. Other options have a different valency of E.

A molecule of ammonia (NH₃) has only single bonds. The atomic number of N is 7. Its electronic configuration is ȷ2, Ǩȸ so it needs 3 more electrons to complete its octet.

Reaction between an acid and an alcohol results in the formation of ester, and the reaction is named as esterification.

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

Because it is a covalent compound formed by sharing of electrons. Whereas in other three compounds are ionic compounds and they conduct electricity in their molten state.

Na (sodium) possesses all the above properties. It is too soft and can be cut with a knife.. It also reacts with water and burns due to the vigorously formation of hydrogen gas.

Some of the metals like aluminium (Al) metal forms amphoteric oxide (Al₂O₃), which can behave like acid as well as base.

Lead readily reacts with the atmosphere.it conducts heat very slowly.