In the chemical reaction below, calcium (ca) and water (h2o) react to form calcium hydroxide (ca(oh)2) and hydrogen gas (h2).
ca (s) + 2h2o (l) ca(oh)2 (aq) + h2 (g)
calcium and water are the reactants in this chemical reaction, whereas calcium hydroxide and hydrogen gas are the products that are formed. once the reaction reaches completion,

a. the total mass of the products will be equal to the original mass of the reactants.

b. the total mass of the products will be greater than the original mass of the reactants.

c. the products of the reaction will have changed back into the reactants.

d. the total mass of the products will be less than the original mass of the reactants.

Transmission electron microscope are best for viewing a) microorganisms in pond water b) internal organs of a mouse c)internal structures of a cell d) surface features of a specimen

Me brainliest 1. what does a red shift mean? blue shift? 2. describe the big bang theory. according to this theory, how old is the universe? 3. scientists believe the universe is expanding. what is the evidence that supports this? 4. describe a nebula.5. describe the 3 types of galaxies. what is a barred spiral galaxy? 6. what is a light year? how far is alpha centauri from earth? 7. describe the universal law of gravitation. be sure to include gravitational force between two objects.8. describe the planets’ orbits around the sun.9. what is the asteroid belt? where is it located? 10. describe rotation and revolution of earth. what determines an earth day and year? 11. how do galaxies exist? 12. compare and contrast the inner and outer planets.13. what causes the seasons?

Ihave no idea how to solve these. plus there's another question that is 2) a 10 kilogram meteorite is collected in space and brought back to earth. it is composed of 1.25 kg of uranium-238 and 8.75 kg of lead-206. how many u-238 half lives have passed? what is the approximate age of the meteorite?