For a hydroxide ions in water is it base or acid or both

When the oxygen produced by photosynthetic plants in the water dissolves in the water, which of these is being formed?

What chemical speeds up the process of decomposition in dead organisms are exposed to it? nitrogen oxygen hydrogen chlorine

Been sitting here trying to take this test and don't know this answer! place the events of a feedback mechanism associated with body temperature in the correct order. ·nerve cells send message from skin to the brain ·body returned to normal temperature around 98.6 degrees f ·temperatures regulation center in the brain sends out signals ·body temperature exceeds 98.6 degrees f ·sweat glands throughout the body activate to cool off skin surface it is a 1 through 5 question in biology!