Part A Which of the following groups comprise the s-block of elements? View Available Hint(s) A) groups 3-12 B) group 18 C) groups 13-18 D)groups 1 and 2

D)groups 1 and 2

Explanation:

The s-block of elements are made up of those chemical elements we can find in groups 1 and 2 on the periodic table.

A periodic table of element is based on the periodic law which states that "the properties of elements are a periodic function of their atomic number".

In the table;

The s-block consists of elements in groups 1 and 2 having an outermost ""ns"" shell configuration. They are predominantly metals.

For Option A, groups 3-12 is the D-block

Option B, group 18 is filled with noble gases and it makes up the p-block

Option C, group 13-18 is makes up the p-block too.

So, the s-block is made up group 1 and 2 elements.

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