Cr2O3+ 2Al -----------> 2Cr+ Al2O3
Cr2O3--------2Cr.
( oxidation no. of cr +3 to +1 means hain of electron so it act as oxidizing agent)
similarly,
2Al------> Al2O3
( oxidation no. of Al +1 to +3 means loss of electron so it act as reducing agent)
Answer: Hydrogen and helium
Explanation:
1 mole of any substance contains Avogadro's number.
So, 1 mole of O2= 6.023x10^23 molecules
3 mole of O2= 6.023x10^23x3 molecules
= 1.8069x10^24 molecules
Each molecule of Oxygen has 2 atoms.
therefore,
1.8069x10^24 molecules= 1.8069x10^24 x 2 atoms
= 3.6138x10^24 atoms.
I have attached a photo of the structure.
You can get better at solving problems like this by practicing a lot!
Nitrogen. air consists 78% of nitrogen gas
