The critical value(s) of z for a two-tailed test at a 0.10 level of significance is?

For a two-tailed test at a 0.10 level of significance, you would divide the significance level by 2, giving 0.05 for each tail. The critical z-values corresponding to 0.05 in each tail are approximately ±1.645. Therefore, the critical values of z for this test are -1.645 and +1.645.