People have developed models of the universe for thousands of years. Identify two observations that a model of the universe would need to explain in order to be useful

What is the porcent of H in NH3

Find the oxidizing agent and the reducing agent. 2Na (aq) + 2H2O (l) →2NaOH (aq) + H2 (g) C (s) + O2 (g) →CO2 (g) 2MnO-4 (aq) + 5SO2 (g) + 2H2O (l) →2Mn2 + (aq) + 5SO2-4 (aq) + 4H + (aq)

The first-order decay of radon has a half-life of 3.823 days. How many grams of radon remain after 7.22 days if the sample initially weighs 250.0 grams?

What evidence is there to suggest that the earth is made up of tetonic plates

The half-life of cesium-137 is 30 years. Suppose we have a 40 mg sample. Exercise (a) Find the mass that remains after t years. Step 1 Let y (t) be the mass (in mg) remaining after t years. Then we know the following.

Which describes the polarity in a water molecule? a). partial negative charge on the oxygen atom because its electrons are pulled toward the hydrogen atoms b).

To what temperature in kelvin will a 2.3 L balloon have to be heated to expand to a volume of 400 L Assume the initial temperature of the balloon is 25 degrees celsius.

In which changes of state do atoms lose energy?

Can you live without body tissue? This is a yes or no question, no explaining required, but you can add it if you want. : D

According to the graph, which activity has used the largest amount of water over the past twenty years?