Worksheets2ND QUARTER REVIEWER
Total questions: 15
Worksheet time: 6mins
In the compound H2O2, why is the oxidation number of oxygen -1, not -2?
Hydrogen is always +1.
The compound is unstable.
The compound is a peroxide.
Oxygen can have variable oxidation states.
How can the oxidation number of an element in a compound be determined?
By knowing the __________.
charge of the compound.
electronegativity of the element.
oxidation numbers of other elements in the compound.
All of the above.
How do you determine the charge on a transition metal ion in a compound like FeCl2?
By ____________.
using a periodic table
using a Roman numeral
knowing the group number of iron
knowing the charge on the chloride ion
Why do ionic compounds form when metal and non-metal elements combine?
Due to ___________.
electron transfer creating opposite charges
electron sharing between atoms
covalent bond formation
van der Waals forces
Why was Avogadro's number chosen to be 6.022×1023?
It was randomly selected.
It's based on the mass of hydrogen.
It represents Earth's atmospheric pressure.
It relates to the number of atoms in 12g of carbon-12.
How would you explain the balanced equation 2𝐻2+𝑂2→2𝐻2𝑂 in terms of conservation of mass?
The number of atoms changes but mass remains constant.
Both mass and atoms remain unchanged throughout.
The number of atoms on each side must be equal.
The reactants gain mass during the reaction.
How does a neutralization reaction demonstrate conservation of charge?
maintaining equal numbers of positive and negative ions
releasing energy in the form of heat
changing the color of indicators
producing water molecules only
Why does a combustion reaction often result in an increase in entropy of the system?
Because it ________________
releases heat energy only
decreases molecular movement
absorbs energy from surroundings
converts solid fuel into gaseous products
How does the presence of a catalyst affect the activation energy in a chemical reaction?
It provides an alternative reaction pathway with lower activation energy.
It changes the overall energy of products.
It increases the activation energy barrier.
It makes the reaction more endothermic.
Which explains the spontaneous nature of rusting despite being a slow process?
The high activation energy barrier.
The presence of water as a catalyst.
The negative Gibbs free energy change.
The formation of complex intermediates.
How does the concentration of reactants affect reaction order?
It has no effect on reaction order.
It changes the reaction mechanism.
It determines the activation energy.
It influences the rate equation exponents.
Which explains the color change in redox reactions?
change in oxidation states of transition metals
formation of precipitates
release of heat energy
changes in pH levels
What distinguishes a combustion reaction from other oxidation reactions?
It _______________________.
occurs rapidly with heat and light
always produces carbon dioxide
only occurs with hydrocarbons
requires a metal catalyst
Researchers at a pharmaceutical company have developed a radioactive tracer to detect early-stage tumors. The tracer has a molar mass of 178.2 g/mol. If 7.94 g of the tracer is produced for a series of experiments, how many individual molecules of the tracer are available for the researchers to use?
(Use this format example: 1.23 x 10^45
(a)
Balance this equation:
NaBr + Ca(OH)2 ---> CaBr2 + NaOH
(Write down the coefficient only: 1,2,3,4)
(a)
