Whcih of the following are invalid variables names and why

BASICSALARY -  Valid

_basic - Valid

basic-hra - Invalid - should not use hyphen

#MEAN - Invalid - No special characters

group. - Invalid - No Special characters

422 - Invalid - Only numbers are not allowed , should start with alphabet

population in 2006 - Invalid - No Spaced are allowed

over time - Invalid - No spaced are allowed

mindovermatter- valid

FLOAT - valid

hELLO - valid

queue. - Invalid - No special characters allowed

team'svictory - invalid - no special characters allowed

Plot#3 - Invalid - no special characters allowed

2015_Dday - Valid