No, all adjectives are not participles. Some participles can be used as adjectives (but not always).
Examples:
Closed doors (closed is the past participle of the verb to close)
Slithering snakes (slithering is the present participle of to slither)
The chief adjective is the past participle, understood. The present participle, understanding, can be an adjective meaning demonstrating that quality.
There is no participle as it is not a verb. It's an adjective.
The adjective is respectful.The present participle of the verb is also an adjective: respecting.The past participle of the verb is also an adjective: respected.
The adjective forms are the present participle (specifying) and the past participle (specified) of the verb to specify.
No, the word old is an adjective, not a participle.
The adjective forms of the verb to trap are the present participle, trapping, and the past participle, trapped.There is not adjective form of the noun trap.
The past participle of the verb "to knife" may be an adjective. It is knifed (stabbed with a knife).The present participle (knifing) does not seem to be used as an adjective.
No, it is not an adjective. Overthrow is a verb. The past participle, "overthrown" can be an adjective.
No, "shut" is a verb or a past participle, not an adjective.
No, it is a verb. The participle (chosen) can be used as an adjective.
No, "amazing" is an adjective not a verb and so it can't have a participle.
No. The word "vast" is a straightforward adjective, not a participle.