A sample of 1.7×10^23 molecules of silicon is moles.

0.28moles of silicon

Explanation:

Given parameters:

Number of molecules of silicon  = 1.7 x 10²³molecules

Unknown:

Number of moles of the silicon  = ?

Solution:

A mole of any substance contains the Avogadro's number of particles.

   1 mole of a substance contains 6.02 x 10²³molecules;

  So;

     1.7 x 10²³molecules contains   = 0.28moles of silicon

answer: the value of enthalpy change will be -152.80 kj.

solution:

pressure = 1atm , temperature = = 298 k

given that pressure and temperature are same in both gases , the number of moles of both gases can be determined by the ideal gas equation.

according to reaction 3 moles no are reacting with 1 mol of ,then 0.49 mol of no will react with moles of ozone that is 0.16 moles of ozone. since, no is limiting reagent and is an excessive reagent.

enthalpy change for the reaction between the given volumes of the gases is :

it would be d. henry moseley

hope this !

and sorry if i'm late. have a good rest of your day! : d