Dalton's atomic theory (1808) provided a framework for the laws of chemical combination—conservation of mass, constant composition, and multiple proportions. The law of multiple proportions states that when two elements form more than one compound, masses of one that combine with fixed mass of the other are in small whole number ratios. Dalton proposed atoms combine in simple whole number ratios to form compounds.
Assertion (A): Leguminous plants do not require nitrogenous fertilizers. Reason (R): They have Rhizobium bacteria in their root nodules that fix atmospheric nitrogen.
A.A is false but R is true.
B.A is true but R is false.
C.Both A and R are true and R is the correct explanation of A.
D.Both A and R are true but R is NOT the correct explanation of A.
Explanation:
Leguminous plants (like peas, beans) have a symbiotic relationship with Rhizobium bacteria in their root nodules. These bacteria convert atmospheric N₂ into usable nitrogen compounds, fulfilling the plant's nitrogen needs. Thus, they generally do not need external nitrogenous fertilizers. Both statements are correct and R explains A.
Explanation:
In PH₃, phosphorus forms three covalent bonds with three hydrogen atoms, so its valency is 3. It has one lone pair. Its electronic configuration is 2,8,5; shares three electrons.
No comments yet. Be the first to start the discussion!