When an acid reacts with a carbonate or metal hydrogen, it forms salts, carbon dioxide gas and water accordingly. Which of the following equations is correct for this chemical reaction?
A.
Na 2CO 3(s) + HCl(aq) → 2NaCl (aq) + H 2O(l) + 2CO 2(g) + H 2O (l)
B.
Na 2CO 3(s) + HCl(aq) → NaCl (aq) + H 2O(l) + CO 2(g)
C.
Na 2CO 3(s) + 2HCl(aq) → 2NaCl (aq) + H 2O(l) + CO 2(g)
D.
Na 2CO 3(s) + 2HCl(aq) → 2NaCl (aq) + H 2O(l) + 2CO 2(g)
The least common multiple and highest common factor of two numbers are 90 and 9 respectively and one of those numbers is 18. What is the second number:
The elevation angle of the tower is 30° from the 18 m high top of a platform. If the height of the tower is 78 m, then what is the distance of the tower from the platform?
