Напишите структурные формулы изомерных ацетиленовых углеводородов состава С7Н12, главная цепь которых состоит из пяти углеродных атомов, и назовите их.

Реакция обмена: zn + 2agno3 = 2ag + zn(no3)2 предположим, что цинк вступил в реакцию полностью, тогда m(ag) = 108*2*25/65 = 83 г. полученный результат противоречит условию , следовательно, порошок, полученный в ходе реакции, состоит из смеси цинка и серебра. примем массу прореагировавшего цинка за х. тогда масса образовавшегося серебра: 108*2*х/65 = 3,32х масса непрореагировавшего цинка (25-х) г. составим уравнение: (25-х) + 3,32х = 26,51. отсюда х=0,65 г находим массу нитрата цинка: m(zn)/[n(zn)  * m(zn)] = m(zn(no3)2)/[n(zn(no3)2) * m(zn(no3)2)] => m(zn(no3)2) = m(zn) *  n(zn(no3)2) * m(zn(no3)2)/[n(zn)  * m(zn)] = 0,65   * 189/65 = 1,89 г масса исходного нитрата серебра: 0,65 * 2 * 170/65 = 3,4 г масса раствора  после реакции: 100 - 3,4 + 1,89 = 98,49 г находим концентрацию раствора: (1,89/98,49)*100%   = 1,92%

papers are usually  delivered  at 8 in the morning, they are being looked through at the moment and you’ll get yours soon. 2. dresses are made preferably of cotton in hot countries. this wonderful costume is being made specially for this performance now. 3. what strange sounds! – oh, our piano is being tuned. 4.where is your car? – it is being filled in the garage at the moment. 5. tea is usually laid on the balcony in fine weather. 6. we are finishing the last preparations for the party: the lights are being switched on, the floors are being cleaned, the tables are being laid. do you think we’ll be ready on time? 7. i’ve got two questions to you. first: “what language is spoken all over the word? ” second: “what language is being spoken in this room? ” 8. the witness is being questioned by the police-inspector now. 9. the old motor-way is used by many people, but it’s not very convenient, that’s why a new ring-road is beind built in the city. 10. our luggage is being examined at the customs now. any luggage going abroad is usually checked  here. 11. we are given a lot of advice by our parents. 12. all the contracts are signed by the president. 13. you’ll have your copy soon, the contract is being typed. 14. you can’t use the fax now, it is being fixed. 15. lots of people are operated on in this clinic. and now unfortunately my uncle john is being operated on here. 16. most cameras are made in japan. 17. what are you doing here in the hall? – my room is being cleaned. 18. can you hear footsteps behind? we are being followed. 19. this bill is often referred to. 20. he is such a nice chap. why is he so often laughed at?