Why would the ending "-ого" be used in the genitive of the adjective тихий (тихого) while the ending "-его" be used in the genitive of such an adjective as хороший (хорошего) since both adjectives end in an unstressed final stem consonant being one of (ж,ш,ч,щ,г,к,х)?
1 Answer
Let's consider the group of adjectives with the stress on the stem ending with г, к, х, and ж, ш, ч, щ. The adjectives with a stem ending in letters к, г, х, ж, ш, ч, щ have the masculine singular ending -ий (маленький - small), the feminine singular ending in -ая (маленькая), and the plural ending -ие (маленькие).
BUT:In the neuter singular such adjectives end in -oe after г, к, х (маленькое), and end in -ee after ж, ш, ч, щ if the stress is on the stem (свежее молоко - fresh milk) That's where the difference starts.
The group with г, к, х will have the following endings.
Долгий, долгого, долгому. Мягкий, мягкого, мягкому. Тихий, тихого, тихому.
The other group with ж, ш, ч, щ will have the following endings.
Хороший, хорошего, хорошему. Горячий, горячего, горячему. Свежий, свежего, свежему. Блестящий, блестящего, блестящему.