Question

how can be prepare sodium carbonate

Answer 1

Sodium carbonate= Na2Co3.10(H2O) [WASHING SODA]
Sodium carbonate can be obtained by heating baking soda, recrystallisation of sodium carbonate gives washing soda
Na2CO3+10(H2O)---->Na2CO3.10(H2O)

Answer 2

Sodium carbonate, also known as washing soda can be prepared by heating sodium bicarbonate over 200 degree Fahrenheit, the products obtained will be Carbon dioxide, water and most importantly sodium carbonate.
It can also be obtained from carbonic acid but now I'm not going that far.

Hope this helps you...