لطلاب الثانوية العامة لغات..راجع إجابتك على أسئلة الكيمياء

قدمنا لطلاب الثانوية العامة لغات أمس بعض الأسئلة فى مادة الكيمياء ليختبر كل منهم نفسه فى إجابتها من إعداء الأستاذ الدسوقى منصور مدرس المادة، واليوم نقدم لهم الإجابات النموذجية لتلك الأسئلة.

(D) Give reasons for :

1- Transition elements have different oxidation states .

2- Transition elements have ideal catalytic activity .

3- Violet vapours are evolved when concentrated sulphuric acid reacts with Potassium iodide with heating .

4- The presence of a huge no. of organic compounds .

5- Alkanes are saturated compounds while alkenes are unsaturated compounds .

(E) 1- When a solution of sodium hydroxide is added to three salts of chloride solution the following results appears :

The first : White gelatinous precipitate . The second : Reddish brown precipitate .

The third : greenish white precipitate .

Mention the basic radical for each one of the three salts and write the equations of the reactions .

2- Dilute hydrochloric acid is added to three solid salts of sodium metal, the following observations appear :

The first : a gas evolves which has irritating smell and turns a paper wet with acidified potassium dichromate from orange to green.

The second : A colourless gas evolves and turns into reddish brown at the top of the tube .

The third : A colourless gas evolves and a yellow precipitate is formed .

Mention the acidic radicals for the three salts and write the equations of the reaction .

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