(a) Calculate the gram molecular mass of water from the values of gram atomic mass of hydrogen and oxygen.
Gram atomic mass of hydrogen $= 1 g$
Gram atomic mass of oxygen $= 16 g$
(b) Modern atomic theory takes up the wave concept, principles of uncertainity and other latest discoveries to give a clear-cut picture about an atom. State any three findings of modern atomic theory.

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Solution

(a)Gram molecular mass of water
It has 2 atoms of hydrogen and 1 of oxygen.
$∴ G r a m m o l e c u l a r m a s s = 2 \times 1 + 16$ =18g,

(b) The findings of modern atomic theory are:
(i) Atom is considered to be divisible particle.
(ii) Atoms of the same element may not be similar in all respects
eg: Isotopes $C l_{17}^{35}$ and $C l_{17}^{37}$
(iii) Atoms of different elements may be similar in some respects.
eg: Isobars $C l_{40}^{18}$ and $C l_{40}^{20}$
(iv) Atom is the smallest particle which takes part in chemical reactions.

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Similar questions

Q. The modern atomic theory takes up the wave concept, principle of uncertainty and other latest discoveries to give a clear-cut picture about an atom. State the findings of modern atomic theory.

Q. Calculate the gram molecular mass of water from the values of gram atomic mass of Hydrogen and of Oxygen.
Gram atomic mass of Hydrogen

= 1 g

Gram atomic mass of Oxygen

= 16 g

Q. (a) Calculate the gram molecular mass of water from the values of gram atomic mass of hydrogen and of oxygen.
Gram atomic mass of hydrogen

= 1 g

Gram atomic mass of oxygen

= 16 g

(b) Atoms and molecules are the building blocks of matter. List out any three differences between them.

Q. Calculate.
(A) Mass of 1.5-gram atoms of calcium. (Atomic mass = 40)
(B) Gram atoms in 12.8 g of oxygen. (Atomic mass = 16)

Gram Atomic mass is just the atomic mass expressed in grams ...ie, atomic mass with gram as units. Our book says that gram atomic mass and gram atom are the same thing (similarly for gram molecule and gram molecular mass) . But later a formula is given that : Gram atom = mass in grams / Atomic mass [RAM].

There are questions also that use this formula ( similarly for gram molecule) in which we have to find the number of "gram atoms " in a given mass of substance.

So what is the real meaning of gram atom and the formula ( and is is similar for gram molecules) ?

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