basic concepts of chemistry

Question 1

law of conservation of mass

Answer 1

in a chemical change mass is neither created nor destroyed

Question 2

law of conservation of mass proposed by

Answer 2

lavoisier

Question 3

law of definite proportions or constant composition

Answer 3

elements always combine in fixed ratio of their weights.

Question 4

law of definite proportions proposed by

Answer 4

proust

Question 5

law of multiple proportions

Answer 5

if two elements form two or more than two compunds between then the masses of one of the elemts which combines with the fixed mas of the other bear a simple whole number ratio

Question 6

law of reciprocal proportions

Answer 6

the ratio of the masses of two elements A and B which combine separately with the fixed mass of element C is either the same or simple multiple of proportions of the masses in which A and B directly combine with each other.

Question 7

law of reciprocal proportions proposed by

Answer 7

richter

Question 8

gay lussac’c law of gaseous volumes

Answer 8

when gases combine they do so in a simple ratio by volume, provided the gases are at the same temperature and pressure.

Question 9

avagadro’s law

Answer 9

equal volumes of gases at equal temperature and pressure contain equal number of particles.

Question 10

1 a.m.u =

Answer 10

1.66*10^-24 g

Question 11

avagadro’s number

Answer 11

6.02*10^23

Question 12

number of moles of a substance=

Answer 12

number of particles/avagadro’s number

Question 13

number of molecules=

Answer 13

volume of gas in litres at NTP*avagadro’s number/22.4

Question 14

the reagent which gets consumed and limits the amount of product formed

Answer 14

limiting reagent

Question 15

percent yield=

Answer 15

actual yield*100/theoretical yield