Question

Anu wants to boil water quickly in a test tube. On observing the
different zones of the flame, she is not able to decide which zone
of the flame will be best for boiling water quickly. Help her in
this activity.
NCERT Class VIII
Science - Exemplar Problems
Chapter 6. Combustion and Flame

Answer 1

she can boil the water with blue flame

Answer 2

as per the lesson combustion and flame,
heating on blue flame heats it quickly.

pls mark as best if helpful.