Which of the four spheres of the Earth encompasses all of the gases at and above the Earth's surface?
1. Biosphere
2. Atmosphere
3. Lithosphere
4. Hydrosphere

Which metal exist in liquid state and can be cut with knife ?

When the speed of the bottle is 2 m/s, the average maximum height of the beanbag is m.

When the chemicals iron sulfide (fes) and hydrochloric acid (hcl) are combined, bubbles appear from the mixture. 1. does the appearance of bubbles indicate a physical or chemical change? 2. why do the bubbles indicate this change? 3. what property is this?