30. A solid sample contains only CaCO3, and MgCO3. To completely react the CaCO3 and MgCO3
present in the sample. 42.00 cm of 0.088 M
HCI were required. The anhydrous chloride salts
from the reaction, obtained by evaporation of
the filtrate weighed 0.19 g. The mass of CaCO3
present in the solid sample is (C = 12,0 = 16,
Mg = 24, Ca = 40, CI = 35.5 )
(1) 0.05 g.
(2) 0.07 g
(3) 0.09 g
(4) 0.11g
(5) 0.12 g

Which statement about hf is true? it is zero for any compound in its standard state. it is positive when the bonds of the product store more energy than those of the reactants. it is negative when a compound forms from elements in their standard states. it is zero for any element that is in the liquid state.

Which of these statements best explains why space exploration should be encouraged? it prepares humans to live without oxygen. it dispel myths about objects in space. it prevents comets and asteroids from striking earth. it creates technology to absorb harmful radiations in space.

Steam reforming of methane ( ch4) produces "synthesis gas," a mixture of carbon monoxide gas and hydrogen gas, which is the starting point for many important industrial chemical syntheses. an industrial chemist studying this reaction fills a 1.5 l flask with 3.5 atm of methane gas and 1.3 atm of water vapor at 43.0°c. he then raises the temperature, and when the mixture has come to equilibrium measures the partial pressure of carbon monoxide gas to be 1 .0 atm. calculate the pressure equilibrium constant for the steam reforming of methane at the final temperature of the mixture. round your answer to 2 significant digits.