Hi, I believe the answers to these are as follows:
6. Kilometres
7. Grams
8. Kilograms
9. Centimetres
10. Metres
When finding an appropriate measuring unit you want something that's not a small decimal number, like the height of a room being 0.0025 of a kilometre tall, or a massive number of a small unit, like meausring the distance to New York in centimetres.
Hope this makes sense and is found helpful :)