Many Doubts on ports, waves, spring tides, rlys etc

Hello Sir, hope you are doing well. I hav a few doubts...can you please clarify them...

1. Major ports - 12 or 13

2. Upward and downward movement
     of ocean water is :
             a. Waves
             b. Tides
             c. Current

3. Is world geo necessary for
    prelims???

4. Spring tides are caused due to sun
     and moon's gravitational pull in
     opposite directions..is this correct
     sir??

5. Railways has 16 or 17 zones??
    Because India Year Book says 17
    but the internet says 16...even
    NCERT says 16

Regards,
Vrushank Reddy

Dear Vrushank,

1. Government continues to give approval to new ports so their

number is not a concern.. before 2003 12, then became 13, 

in 2013 government gave approval to 2 new ports sagar in wb and

durgarajupalem in ap so that will become 15 + 200 non major ports

Maritime Development Program, Sagarmala project

2. waves move forward but particles move up, down and circular

3. World geo is necessarily to be studied as it is in prelims and also mains

4. Spring tides occur wen S M E or S E M are in straight line called syzygy

5. go by India year book as it is revised every year 

Best Wishes