These would be the elements in row 2 the alkaline metals. Elements in a row usually share many qualities such as electon reactivity as well as similar characteristics like the fact that many alkaline metals are considered Cations, ions with positive charges. Some examples are beryllium and calcium.
You water three sunflower plants with salt water. Each plant receives a different concentration of salt solutions. A fourth plant receives pure water. After a two-week period, the height is measured. i think the indepent variable is sunflower ... variable is height measured and the control variable is the fourth plant.
The producers at the beginning of the Earth's food chain are plants.
Earth’s global temperature has changed greatly in the past hundreds of years. This is due to how much energy the planet is receiving from the sun and how it radiates back. Another cause is humans, due to deforestation, burning of fossil fuels, pollution, etc.
