Question

how many molecules are present there in 140g of mgo​

Answer 1

MgO=24+16=40g
Moles=mass/molar mass
=140/40=3.5moles
Molecules in 1 mole=6.023*10^23
=3.5*6.023*10^23
=21.0805*10^23molecules

Please mark as brainliest and follow me

Answer 2

Answer:

Molar mass of MgO = (24+16) gm

                                  =40gm

since, 40 gm of MgO contains 6.022 × 10²³ molecules

therefore, 140gm will contain = (6.022 × 10²³ ÷40) ×140

                                                    =21.077 ×10²³ molecules

Explanation: First we will find that weight of  6.022 × 10²³ molecules in MgO i.e it's molar weight or molar mass then we will find out the no. of molecules in 1 gm of MgO and after doing so to find out the no. of molecules in  140gm of MgO we will apply unitary method i.e we will multiply the weight of 1 gm of MgO by 140 to find out the no. of molecules in 140 gm of MgO

HOPE THIS MAY HELP YOU