Изменяется ли число атомов при химической реакции?

Согласно закону сохранения массы веществ число атомов до и после реакции должно быть одинаковым.

Dear Mag,

Thank you for your letter. My name is Helen. My surname is Macklay. I am from the USA. I live with my mum, dad and my sister. We are twins. Our birthday is in spring, on the 21st of May. When is your birthday?

My favourite sport is tennis. Betsy likes it too. I am very energetic! And Betsy is kind and merry. We’ve got two parrots and a cat. We like to take photos of our pets and friends.

We can ride a bike and a scooter.

Can you ride them? What do you like to do?

Please write back.

Your friends,
Helen and Betsy

Santa Clause was very busy in December. He got up early. He washed his face and hands with snow. At 7 a.m. Santa had an ice-cream and a cup of cold coffee for breakfast. Then he gave bread to his deer  Rudolph. Santa took snow and cold weather and sat in the sleigh. He flew  to different countries. He visited forests and fields, rivers and mountains

At 2 p.m. Santa Clause came back home. He read children’s letters and wrote a list of Christmas presents. In the evening Santa made Christmas presents for his friends