Non metals whose 2 forms
1]very hard
2] conductor of electricity

Nonmetals are (usually) poor conductors of heat and electricity, and are not ... When elements combine to form compounds, there are two major types of ... That is, the Group 7A nonmetals form 1- charges, the Group 6A nonmetals form 2- charges ... These attractive forces are very strong, and most ionic compounds therefore ...

Explanation:

Diamond

Explanation:

Diamond has covalent bonds, which makes it a non-metal.

However, it also has a tetrahedral structure, which holds its C atoms together by strong forces, thus making it hard.

Diamond also has free-moving electrons due to its tetrahedral structure, thus making it possible to conduct electricity.

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol