Do 2. A student determines that there are 1.3 x 1025 molecules of an unknown substance in a 968 g sample. Which compound most likely represents this
unknown substance?
CO
CIO
2)
CO2
N203
CLEAR ALL

The correct option is;

CO₂

Explanation:

The given information are;

The number of molecules in the substance = 1.3 × 10²⁵

The mass of the substance = 968 g

Therefore, we have;

The number of molecules in one mole of a substance = 6.02 × 10²³

The number of moles present = (1.3 × 10²⁵)/(6.02 × 10²³) ≈ 21.595 moles

Therefore, 968 g = 21.595 moles

1 mole = 968/21.595 = 44.826 g

The mass of one mole of the substance = 44.826 g

Therefore the mass of one mole of the substance is closely related to the mass of one mole of CO₂ which is 44.01 g/mol.  

The correct option is CO₂

The number of molecules in one mole of a substance should be = 6.02 × 10²³

And,

The number of moles present is

= (1.3 × 10²⁵)/(6.02 × 10²³)

≈ 21.595 moles

Now

1 mole = 968/21.595 = 44.826 g

The mass of one mole of the substance = 44.826 g

So,  the mass of one mole of the substance is closely related to the mass of one mole of CO₂ i.e.  44.01 g/mol.  

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b) nuclear ive learned that in a pedtrodic table

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.