What helps me to balance equations is to list the elements i have on each side of the equation, and use tally marks to see what I have and don't have. Then when I'm done balancing, I tally again to make sure everything matches up.
On the left side, you have 1 Al, and 2 O. On the right side, 1 Al and 3 O.
In order for the equation to balance, you need to place a 2 in front of the AlO on the right side. This would make the Al have 2 atoms and the O have six. On the left side, you need to place a 2 in front of the Al and a 3 in front of the O, making it six. Left side: 2 Al's 6 O's. Right side: 2 Al's and 6 O's. Matches!
Answer:
Phenolphthalein is a chemical compound with the formula C20H14O4 and is often written as "HIn" or "phph" in shorthand notation. Phenolphthalein is often used as an indicator in acid–base titrations. For this application, it turns colorless in acidic solutions and pink in basic solutions.

The element having valency of 1 is ~
Answer:
1.Hydrogenation of Alkenes and akynes.
2.Reaction of alkylhalides.
3. Halogenation.