Q31

1. Z has the lowest melting point in the row. It could be sodium (group I metals have low melting points) or non-metals like chlorine.

2. The chloride of Y can dissolve in water, but the chloride of "chloride", which is chlorine gas, is not very soluble in water. On the other hand, sodium chloride is soluble in water.

3. The oxide of Y has a giant structure and it's a solid at room temperature, and this indicates some ionic or giant covalent structure; this strongly indicates that sodium is likely the element Y. Unlike other giant covalent structures involving carbon, tetrachloromethans (C Cl4) is a simple molecular structure)

So, element Y should be sodium. A possible formula of this compound could be NaCl.

Q27

Option 1

- Heating almost every metal in oxygen would give us a metal oxide, and barium is no different

-Barium oxide, being a basic oxide, is capable of reacting with dilute hydrochloric to form soluble barium chloride salt

- Upon the addition of soluble dilute sulfuric acid, a white precipitate of barium sulfate is formed (a precipitation reaction)

- Filtering gets us the solid barium sulfate we need, while washing and drying removes any unwanted impurity.

- So, it's clear that the first reaction is capable of obtaining a pure, dry sample of barium sulfate

Option 2

- Barium nitrate is able to decompose to form barium oxide, even if air is not present in great quantities

- Barium oxide is a generally soluble basic oxide forming barium hydroxide

- The resulting soluble barium hydroxide can react with dilute sulfuric acid to form barium sulfate in a similar process to Option 1

- So, option 2 is also possible

Option 3

Similar, and I believe that all we need to bother about is the barium sulfate salt being insoluble since the reagents of barium are mostly soluble in water

All three reaction routes are possible, but the first reaction seems dangerous to be conducted in my opinion

thx :) are you able to help with some questions today?