Answer:
(a). Number of protons in a chlorine atom = 17
(b). Atomic number of sodium = 11
Step-by-step explanation:
Let the number of protons in a sodium atom = <em>x</em>
Then, the number of protons in a chlorine atom =<em> x</em> + 6
Now, it is given that the atomic number of an element is equal to the number of protons per atom.
So, atomic number of sodium (Na) = <em>x</em>
Atomic number of chlorine (Cl) = <em>x</em> + 6
It is given that the atomic number of chlorine is 5 less than twice the atomic number of sodium.
∴ atomic number of chlorine (Cl) = 2 × atomic number of sodium (Na) - 5
⇒ <em>x</em> + 6 = 2<em>x</em> - 5
⇒ <em>x </em>- 2<em>x</em> = -5 - 6
⇒ -<em>x</em> = -11
Cancelling the minus sign from both sides, we get
<em>x</em> = 11
(a). Number of protons in a chlorine atom = <em>x</em> + 6
= 11 + 6 (∵ <em>x</em> = 11)
= 17
(b). Atomic number of sodium = <em>x</em> = 11
