Science: 2016: CBSE: [Delhi]: Set – II

(a) Ethanol

(b) Ethanal

DNA is deoxyribonucleic acid. It is the hereditary material present in all living organisms (except viruses)and carries genetic traits from parents to their offspring.

The two biotic components of a biosphere are:
i. plants and,
ii. animals

A ray of light parallel to principal axis appears to pass from the focus of the convex mirror after reflection.

 

Active participation of local people helped to conserve forestsand wildlife.The followingare the examples:

i. In 1731, Amrita Devi Bishnoi from Khejri village established a group of 363 people who sacrificed their lives for the protection of khejri trees.

ii. In 1970, SunderlalBahuguna initiatedChipkoAndolan, in which women hugged the tree trunks with their arms, thereby preventing the workers from cutting down the trees.

iii. In 1972, the forest officer (A.K. Banerjee) along with the people of local community recovered the badly degraded Sal forests of Arabari.

The four advantages of properly managed watershed management are:
i. It helps to maintain equal and sustainable distribution of water.
ii. It enhances the level of groundwater.
iii. It maintains the quality of water.
iv. It provides protection from floods by controlling the flow of rainwater.

Oxidising agent is a substance which can give oxygen to other substances.

When an oxidising agent is added to Propanol, it is oxidised to Propanoic acid.

 

Covalent compounds are those compounds which are formed by sharing of electrons between two atoms or the compounds which contain covalent bonds.

Covalent compounds are different from ionic compounds because the ionic compounds are formed by the transference of electrons.

Three characteristics of covalent compoundsare as follows:

(i)Generally they have low melting and boiling points.

(ii) Generally they are insoluble or less soluble in water but soluble in organic solvents.

(iii)They do not conduct electricity.

The electronic configuration (2, 8, 2) of the element ‘M’ suggests that itbelongs to group 2 (presence of 2 electrons in valence shell) and period 3 (presence of 3 shells) of the Modern Periodic Table and its valency is 2.

The chemical formulas of three compounds are –

M (NO₃)₂ , MSO₄ , M₃ (PO₄)₂respectively.

‘M’ will form ionic compounds by losing two electrons present in the valence shell.

Two elements of group 1 are sodium (Na) and  potassium (K).

Electronic configurations of sodium is  2,8,1 and that of potassium is 2,8,8,1.

Similarity between sodium and potassium : Both have one valence electron.

The formula of oxide of sodium is Na₂O  and that of potassium is  K₂O.