How many moles in 28 grams of uo2?

There are 0.135moles of UO2 in 28 grams of UO2

Explanation:

The SI base unit for amount of substance is the mole. 1 mole is equal to 1 mole UO2, or 207.03grams.

This is the molar mass of UO2, calculated from the sum of the molar masses of uranium and oxygen.

That is, molar mass of UO2= molar mass of U + (molar mass of O)2

=238.03g/mol + (16g/mol)2

= 238.03g/mol + 32g/mol= 270.03g/mol

Molar mass of UO2= 270.03g/mol

This implies that 1 mole of UO2 has a mass of 207.03 grams

Number of moles of UO2 = mass of UO2/ molar mass of UO2

Mass of UO2= 28 grams

Number of moles of UO2= 28 g/ 207.03gmol-1

Number of moles =0.1352 moles of UO2

Therefore, there are 0.135 moles of UO2 in 28 grams of UO2.

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

he would use the colour black