The hydrogen gas generated when calcium metal reacts with water is collected over water at 20. °c. The volume of the gas is 641 ml and the pressure is 988 mmhg. What is the mass (in grams) of the hydrogen gas obtained? the vapor pressure of water at 20. °c is 17. 54 mmhg.

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Tortoise shells and snail shells are similar in function: they protect the organism from predators. based on a comparison of the organisms in the images, what can you conclude? 1. tortoises and snails have homologous organs, and they’re evolutionarily related. 2. tortoises and snails have homologous organs, and they belong to same species. 3. tortoises and snails have analogous organs, and they belong to the same species. 4. tortoises and snails have analogous organs, and they don’t belong to the same species. 5. tortoises and snails have analogous organs, and they aren’t evolutionarily related.

In this food web, which group would increase in number if snakes were eliminated? a. producers b. decomposers c. primary consumers d. secondary consumers e. tertiary consumers