a scientist is creating a new synthetic material. the material’s density is 6.1 g/cm3. which sentences describe how the scientist can lower the material’s density? a)the scientist can decrease the mass while keeping the volume constant.
b)the scientist can increase the mass while keeping the volume constant.
c)the scientist can decrease the volume while keeping the mass constant.
d)the scientist can increase the volume while keeping the mass constant.

Explanation:

Density is defined as the amount of mass present in per unit volume of a substance.

Mathematically,       Density =

Since, density is directly proportional to mass. Hence, when we increase the mass then there will be increase in the density of material. But when we decrease the mass of a material the its density will decrease.

On the other hand, density is inversely proportional to volume. Therefore, an increase in volume of a material will lead to a decrease in its density.

Thus, we can conclude that following sentences describe how the scientist can lower the material’s density.

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