Which statement is true?
a. a molecule having a covalent bond can be ionic
b. a molecule having a covalent bond is always polar
c. a molecule having a covalent bond may be polar or nonpolar
d. a molecule having a covalent bond i =s always nonpolar

the equation that correctly represent the reaction for formation of ammonia is

n2+ 3h2 → 2nh3 (answer d)

1 mole of nitrogen gas (n2) react with 3 moles of hydrogen gas (h2) to form 2 moles of ammonia ( nh3). this is in a process known as haber process were iron is used as a catalyst and reaction take place that a higher temperature and pressure. the process is exothermic hence energy is released.

the answer is:  

line graphs show patterns in data with variables that change over time; whereas, circle graphs show data as parts out of a whole (such as out of 100%).