Q2 of 12 Page 55

Give reasons.

All the mass of an atom is concentrated in the nucleus.

All the mass of an atom is concentrated in the nucleus:

i. In the Rutherford’s model, since most of the alpha rays went straight and pass through the gold sheet.


ii. This means that there must be a very large empty space within the atom.


iii. The positively charged heavy mass which occupies only a small volume in an atom is called nucleus. It is supposed to be present at the center of the atom.


iv. Thus, most of the mass of the atom is concentrated in the nucleus.


More from this chapter

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2

Give reasons.

During ion formation, an electric charge develops on the elements.

 2

Give reasons.

Why does ionization take place?

 3

Fill in the blanks.

(a) If the valency of carbon is 4 and that of hydrogen is 1 then the molecular formula of methane is ………………


(b) There are two electrons in the outermost orbit of the magnesium atom. Hence, the valency of magnesium is ………………


(c) 35 Cl and ……………… are isotopes of chlorine.


(d) Isotopes of uranium are used as ……………… in atomic reactors.

 4

Match the following.