When a substance is oxidized, it
Loses electrons
Gains oxygen atoms
Gains electrons
Loses protons (H+ ions)
Correct answer is A
When a substance is oxidized, it loses electrons. Oxidation is a chemical reaction that involves the moving of electrons. Specifically, it's a process that involves the substance losing electrons. This is an old definition of oxidation, based on the oxygen's role in reactions. The modern definition of oxidation involves an increase in oxidation state by a molecule, atom, or ion.
What is the symbol used to represent an alpha particle?
α
γ
δ
β
Correct answer is A
An alpha particle is represented by the Greek letter 'α'. Alpha particles are a type of ionizing radiation ejected by certain types of radioactive materials. They consist of two protons and two neutrons, so they can be represented as a Helium-4 nucleus.
Which of the following is a common property of non-metals?
Exist as solids at room temperature
Tend to gain electrons in chemical reactions
High thermal conductivity
Readily form cations in chemical reactions
Correct answer is B
Tend to gain electrons in chemical reactions. Non-metals typically have a high electronegativity and tend to gain electrons to achieve a stable electron configuration. This results in the formation of negatively charged ions (anions) during chemical reactions.
25%
12%
75%
50%
Correct answer is C
The molar mass of methane (CH4) is calculated by adding the atomic masses of carbon (approximately 12 g/mol) and hydrogen (approximately 1 g/mol). Therefore, the molar mass of CH4 is 12 g/mol + 4 x 1 g/mol = 16 g/mol. The mass percentage of carbon in CH4 is given by (mass of carbon / total mass) x 100% = (12 g / 16 g) x 100% = 75%.
What type of reaction is involved in the formation of alkanols from alkenes?
Elimination reaction
Redox reaction
Substitution reaction
Addition reaction
Correct answer is D
Alkanols can be formed from alkenes through an addition reaction. In this reaction, the carbon-carbon double bond of the alkene is broken, and a hydroxyl group (-OH) is added to one of the carbon atoms, resulting in the formation of an alcohol.
What is the common name for ethanoic acid?
Acetic acid
Butyric acid
Propionic acid
Formic acid
Correct answer is A
Ethanoic acid is commonly known as acetic acid. It is the main component of vinegar and is used in various industrial processes.
Chromatography
Filtration
Decantation
Distillation
Correct answer is A
Chromatography is a separation technique used to separate and analyze components of a mixture based on their differential partitioning between a stationary phase (e.g., paper or a column) and a mobile phase (e.g., solvent). Different components move at different rates, leading to separation.
C\(_4\)H\(_8\)O\(_4\)
CH\(_2\)O
C\(_2\)H\(_4\)O\(_2\)
C\(_3\)H\(_6\)O\(_3\)
Correct answer is B
To determine the empirical formula, we first need to convert the percentages to moles by assuming a convenient mass for the sample. Let's assume we have 100 grams of the compound.
Mass of carbon = 40.00 grams
Mass of hydrogen = 6.67 grams
Mass of oxygen = 53.33 grams
Now, we calculate the moles of each element:
Moles of carbon = 40.00 g / molar mass of carbon = 40.00 g / 12.01 g/mol ≈ 3.33 mol
Moles of hydrogen = 6.67 g / molar mass of hydrogen = 6.67 g / 1.01 g/mol ≈ 6.60 mol
Moles of oxygen = 53.33 g / molar mass of oxygen = 53.33 g / 16.00 g/mol ≈ 3.33 mol
Now, we find the smallest whole-number ratio of the moles:
C ≈ 3.33 / 3.33 ≈ 1
H ≈ 6.60 / 3.33 ≈ 2
O ≈ 3.33 / 3.33 ≈ 1
Thus, the empirical formula is CH2O.
What is the main source of carbon monoxide (CO) in urban areas?
Volcanic eruptions
Vehicle emissions
Forest fires
Industrial processes
Correct answer is B
The main source of carbon monoxide (CO) in urban areas is vehicle emissions, especially from incomplete combustion of gasoline and diesel in engines.
Which of the following is a primary constituent of crude oil?
Pentane
Ethanol
Heptane
Methane
Correct answer is D
Crude oil is a mixture of hydrocarbons of various chain lengths. methane is one of the primary constituents of crude oil, and it belongs to the group of alkanes.
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