what test of love does clarisse give montag and how does he respond?

Clarisse gives Montag her dandelion test. If there is yellow under his chin, he is in love. She rubs it under his chin and proclaims that he is not in love, 'What a shame,' she said. 'You're not in love with anyone.' Montag insists he is in love. Montag insists he is very much in love and Clarisse says that it doesn't appear so. Montag makes the excuse that ,"she must have used up all the yellow."