Reactive Intermediate question

1.Which of the following readicals have pyramidal shape

(I) CH3 (II) CF3 (III) CD3 (IV) ⧊
(a) I, II (b) I, II, IV (c) III, IV (d) II and IV

2. Spin trapping technique is used for detection of

(a) carbonium ion (b) Free radical (c) Benzyne (d) Carbanion

3.Correct order of stability of free radicals (I-IV) is

(I) H2C CH CH2 •

(II) Me2CH •

(III) Ph •

(IV) Ph3C •

(a) I > IV > II > III (b) IV > I > III > II (c) IV > III > I > II (d) IV > I > II > III