Q. 35.0( 3 Votes )
Match the pairs.<
a. photosynthesis iii) Chemical change
Photosynthesis is a chemical change. Photosynthesis is the process by which glucose is synthesized in the cells by using Carbon dioxide and water as reactants. Since the reactants changes into a different substance that is completely different in properties, it is a chemical change.
b. Water iv) Covalent bond
Water is formed by the sharing of electrons by two hydrogen molecules and one oxygen molecules and forming a covalent bond between them. Since there is sharing of electrons between two atoms, the molecule becomes covalent. The formation of water molecule is shown:
The grey coloured electrons are the shared one.
c. Sodium Chloride v) Ionic bond
During the formation of Sodium Chloride, chlorine atom gains an electron from the sodium atom so as to complete its octet. This results in Sodium being positively charged and Chlorine being negatively charged and thus forms a ionic bond between them. The formation of an ionic bond makes the compound an Ionic compound.
The electron marked X is the one that is lost by sodium and gained by chloride.
d. Dissolution vi) physical change
Dissolution is the process of making a salt soluble in a solvent. During dissolution of a substance, no change is observed in the case of taste, odour or other properties. This makes the dissolution of a substance a physical change.
e. Carbon ii) Reactant in combustion process
Different substances are burnt so as to obtain energy. The most common material that is used for combustion is Carbon. Combustion is a chemical change involving a reaction with oxygen. Since most of the combustible substances are made of carbon, it is in the reactant side. The word equation of this reaction can be represented as:
Carbon + Oxygen Carbon dioxide
f. Fluorine vii) tendency to form anion
An anion is a chemical species that is formed when an element gains an electron. The electronic configuration of Fluorine is 1s2 2s2 2p5. The outer most shell, that is the 2nd shell is not completely filled making Fluorine atom unstable. To become stable, Fluorine must gain an electron so as to complete the octet of its second shell. Hence Fluorine has a greater tendency to form a negative anion.
g. Magnesium i) Tendency to loose electrons
The electronic configuration of Magnesium is 1s2 2s2 2p6 3s2. For Magnesium to have a complete octet, it must either gain 6 electrons or loose 2 electrons. It is easier to loose two electrons and get a completely filled outer shell for magnesium rather than gaining six electrons. For this reason, Magnesium is observed to have the tendency to loose electrons.
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