如图表示的是某纯净物在氧气中燃烧的微观示意图，请根据图示回答问题：

（1）甲的化学式为____ ；

（2）上述微观反应图示中，不发生改变的粒子是____ （填“分子”、“原子”或“离子”）；

（3）生成物中丙和丁两种物质的分子个数比为____ ．

根据短文为文中的六个小伙伴找到他们各自的座位。

 Where do they sit?

    Six children go to the cinema(电影院) to see a new film(电影). The film is about animals. Their seats(座位) numbers are 5A, 5B, 5C, 5D, 5E and 5F. They sit in the same row(排). Sam sits in 5A. John sits in 5C. Helen sits between(在......中间) Sam and John. Sue sits beside John. Where is Mingming? He is between Sue and Mary.

 Where do they sit?

5A ____ 5B____ 5C____ 5D____  5E____  5F____