Which one of the following is called 'syngas'?
- A.C(s) + H2O(g)
- B.CO(g) + H2O(g)
- C.CO(g) + H2(g)
- D.NO2(g) + H2(g)
Correct answer
Explanation
The correct answer is C, CO(g) + H2(g). A mixture of carbon monoxide and hydrogen is called synthesis gas, or syngas, because it is the starting material for making methanol and many other compounds.
Syngas is made by passing steam over red-hot coke or by reacting steam with hydrocarbons such as methane at about 1270 K over a nickel catalyst. When it comes from coal, the process is called coal gasification, and the CO and H2 mixture made from coke and steam is also known as water gas. Passing syngas with more steam over an iron catalyst turns the CO into CO2 and gives extra hydrogen, the water-gas shift reaction.
A is wrong because coke and steam are the raw materials that react to form syngas, not syngas itself.
B is wrong because CO and steam are the reactants of the water-gas shift reaction, which yields CO2 and H2.
D is wrong because nitrogen dioxide and hydrogen have nothing to do with syngas.
Exam tip: syngas or water gas = CO + H2; producer gas = CO + N2.
Practice Questions
View allWhich one of the following frequency ranges is sensitive to human ears ?
- A.0-200 Hz
- B.20-20,000 Hz
- C.200-20,000 Hz only
- D.2,000-20,000 Hz only
Show answer
The normal human ear hears sound from about 20 hertz to 20,000 hertz, the audible range. Frequency, measured in hertz, is the number of vibrations per second, and it decides the pitch of a sound: the higher the frequency, the shriller the note.
Read the full explanation →The frequency of ultrasound waves is
- A.less than 20 Hz
- B.between 20 Hz and 2 kHz
- C.between 2 kHz and 20 kHz
- D.greater than 20 kHz
Show answer
Ultrasound is sound with a frequency above 20,000 Hz, the upper limit of human hearing. Humans hear sound between about 20 Hz and 20 kHz.
Read the full explanation →Which one of the following is an example of a clean fuel ?
- A.Coke
- B.Propane
- C.Petrol
- D.Wax
Show answer
Propane is a light gaseous hydrocarbon that burns completely with a blue flame, leaving no smoke, soot or ash. A clean fuel burns completely, gives high heat and releases few pollutants.
Read the full explanation →A sample of 'soft soap' contains
- A.Caesium
- B.Potassium
- C.Calcium
- D.Magnesium
Show answer
Soft soaps are potassium salts of fatty acids, while ordinary hard bar soaps are sodium salts. Soap is made by saponification, heating an oil or fat with an alkali.
Read the full explanation →Which of the following sets of elements has the same valency?
- A.Na, Mg, Ca
- B.Na, Mg, Al
- C.Mg, Ca, K
- D.Mg, Ca, Ba
Show answer
Magnesium, calcium and barium are all alkaline earth metals of group 2, and each has a valency of 2. Elements in the same group of the periodic table have the same number of electrons in their outermost shell, and so the same valency.
Read the full explanation →