Answer/ explanation :
Mass in grams of 4.26 mol of Si.
To calculate this, we use the formula
Number of mole = mass / molar mass
Since we are given the number of mole
Number of mole = 4.26mol
Mass = ?g
Molar mass of Si = 28.0855g/mol
4.26mol = mass / 28.0855g/mol
By cross multiplication,
Mass = 4.26 * 28.0855
= 119.644g
Therefore, the number of mass in gram of Si is 119.644g