Предмет: Химия, автор: negativ227

Сколько молекул содержат 6 грамм магния (Mg)

Ответы

Автор ответа: Buritoo

n(Mg) = mM = 624 = 0,25 моль
N(Mg) = n*Na = 0,25 * 6 * 10^23 = 1,5 * 10^23 молекул
Na - число Авогадро

Автор ответа: negativ227

Спасибо большое!

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Task 1. Reading Прочтите текст и расставьте события в предложениях по- порядку согласно тексту:

1
2
3
4
5
a. Dogs help police officers.
b. More than ten thousand years ago dogs didn’t live with people.
c. Never let your dog run wild in the street.
d. When you go on holiday, you can leave your dog with a family friend.
e. Now dogs do many good things for people.

Кроме цифр и букв писать ничего не надо!
Dogs
You know that a dog is a man’s best friend. The dog is also man’s oldest friend.
More than ten thousand years ago, dogs didn’t live with people. They were wild. Now dogs live with people and do many good things for them. Dogs can be “eyes” for blind people. There was a dog, Bruno, who saved 40 people in the mountains. Dogs help geologists to find metals. They help police officers to catch criminals.
If you have a dog, you know how clever dogs are. You can teach your dog to do many tricks: to bring things to you, to carry your bag when you do shopping, to help you with your school-bag when you come home from school.
Dogs usually like to swim and you can teach your dog to swim. But you must remember that some dogs are afraid of water.
Where do you leave your dog, when you go on holiday? Leave him in good hands: with a neighbor or a family friend. Take your dog to these people before you go away. Sit down and talk to them. Show your dog that they are your friends and he will like them.
Take care of your dog; never let him run wild in the street. If you are good to your dog, he will be your real friend.

Task 2. Writing
Списываешь предложения, в пропуски вставляешь am, is или are.

My friend …playing in the yard now.
I …writing an exercise at the moment.
Sam and Carla …doing homework at present.
Look! The boy …smiling at us.
Listen! The birds …singing in the garden.

Task 3. Use of English.
Пиши ТОЛЬКО цифру и букву правильного ответа.
Выбери правильный ответ.
1 He ……. to the swimming pool every Sunday.
a) goes b) go c) going
2 It ………… now.
a) rain b) isn`t raining c) doesn`t rain
3 They …in the garden on Wednesday.
a) don`t work b) aren`t working c) don`t works
4 … she … the piano every day?
a) does … playing b) does … plays c) does… play
Кто сделает дам 90 баллов