As you mentioned, one of Daisy's traits is "undecided" and "superficial". You can use two quotes to back this up from this chapter. When Nick invites her to tea, he tells her not to bring her husband, Tom. She replies:
I called up Daisy from the office next morning, and invited her to come to tea.
“Don’t bring Tom,” I warned her.
“Don’t bring Tom.”
“Who is ‘Tom’?” she asked innocently.
Later, when she arrives at Nick's house for tea, she flirtatiously asks Nick:
“Is this absolutely where you live, my dearest one?”
“Are you in love with me,” she said low in my ear, “or why did I have to come alone?”
She shows her superficiality when she remarks, after seeing Gatsby's house from Nick's yard:
“That huge place THERE?” she cried pointing.
“Do you like it?”
“I love it, but I don’t see how you live there all alone.”
“I keep it always full of interesting people, night and day. People who do interesting things. Celebrated people.”
When Daisy sees Gatsby's shirts (he needs to change into a new shirt), she remarks:
“They’re such beautiful shirts,” she sobbed, her voice muffled in the thick folds. “It makes me sad because I’ve never seen such—such beautiful shirts before.”
Her entire conversations with both Nick and Gatsby in this chapter are totally vacuous, lacking any depth or concern for either Nick or Gatsby. It's all about her.
“I adore it,” exclaimed Daisy. “The pompadour! You never told me you had a pompadour—or a yacht.”
The only parts of the conversations that are not about her are about things, possessions, riches.