Is it true that whatever is dry is pure even if there was impurity on it?

The impure material object does not soil (make impure) anything else unless the impurity is wet and transferable. But, if the impurity is dry or non-transferable, then there is no problem. Fuqaha has stated that: There is no disagreement between Muslim scholars that when a dry impurity touches something dry it does not make the latter impure.

Is Zakah due on a woman`s deposited gold?

Zakah (obligatory charity) is due on deposited gold if it reached Nissab (minimum amount liable for Zakah), and a lunar year had lapsed over owning it. The due Zakah is (2.5%). And Allah Knows Best.

Is it permissible to go to the bathroom wearing a necklace that has the word "Allah" inscribed on it?

All Perfect Praie be to Allah, The Lord of The Worlds, and may His Peace and Blessings be upon our Prophet Muhammad and upon all of his family and companions.

Anything that contains words pertaining to Allah, The Almighty, is desired to be left outside when going to the bathroom, or to be hidden for fear of losing it. And Allah Knows Best.

How many prostrations of Quranic recital are there, and is it permissible not to offer them while reciting?

There is one prostration for the Quranic recital, and it is a Sunnah for which one is rewarded upon offering it. However, one who doesn`t isn`t punished. Therefore, those who fail to offer it aren`t considered sinful, rather they deprive themselves from the reward.