Some Basic Concepts of Chemistry

Which chemical fiber, also known as 'Dacron', is used in making crease-resistant fabrics?

Which thermosetting polymer is used to make electrical switches and handles of kitchen utensils?

Chemistry plays a vital role in the production of steel, which is an alloy of which primary metal?

Which inert gas is used to fill balloons and in deep-sea diving because of its low solubility in blood?

Chemistry is fundamental to the 'Ceramics' industry. What is the basic raw material used in making traditional ceramics?

Which of the following is an example of 'Bio-degradable' polymer that chemists have developed to reduce environmental pollution?

Chemistry has helped develop 'Pheromones' for agricultural use. What is their purpose?

The importance of chemistry is also evident in the development of 'Biodegradable Polymers'. Which of the following is a commercially important biodegradable polyester?

Why is the chemical study of 'Enzymes' important for the future of industrial chemistry?

In the chemical industry, 'Atom Economy' is a principle used to evaluate the efficiency of a reaction. A high atom economy is important because it:

In a chemical reaction, the total mass of the reactants is equal to the total mass of the products. This is known as:

Which of the following elements is a non-metal?

Which statement about the particles of matter is FALSE?

If you have a container of oxygen gas ($O_2$), it is classified as:

Which of the following is true for both compounds and elements?

Pure gold is too soft for making jewelry and is often mixed with copper. The resulting jewelry is a:

Which of the following is a chemical change that occurs when a candle burns?

Two elements $A$ (at. mass $16$) and $B$ (at. mass $32$) combine to form a compound. If the ratio of their masses in the compound is $1:1$, the formula of the compound is:

Which of the following is an example of a chemical change occurring during a separation process?

The Law of Multiple Proportions was proposed by:

Which law was validated by the experiment involving the reaction of hydrogen and oxygen to form water vapor in a 2:1 volume ratio?

The Law of Conservation of Mass was originally called the Law of Indestructibility of Matter. Which of the following best describes it?

Pure water consists of $11.11\%$ hydrogen and $88.89\%$ oxygen by mass. This is true for water from any source. This supports:

When $12\,g$ of Carbon reacts with $16\,g$ of Oxygen to form $CO$, and $12\,g$ of Carbon reacts with $32\,g$ of Oxygen to form $CO_2$, the ratio of oxygen masses ($16:32$) is $1:2$. This illustrates:

If an element $A$ forms two compounds with oxygen, $AO$ and $A_2O_3$, what is the ratio of the masses of oxygen that combine with a fixed mass of $A$?

Which of the following is consistent with the Law of Constant Proportions?

In the precipitation reaction: $AgNO_3 + NaCl \rightarrow AgCl + NaNO_3$, if $17.0\text{ g}$ of $AgNO_3$ reacts with $5.85\text{ g}$ of $NaCl$ to produce $14.35\text{ g}$ of $AgCl$, what is the mass of $NaNO_3$ formed?

According to the Law of Definite Proportions, a sample of pure water ($H_2O$) will always contain $11.1\%$ Hydrogen and $88.9\%$ Oxygen by mass. If a sample of 'heavy water' ($D_2O$) is analyzed, the mass percentage of hydrogen (deuterium) will be approximately:

When $100\text{ mL}$ of $N_2$ and $100\text{ mL}$ of $O_2$ are passed through an electric arc, $200\text{ mL}$ of $NO$ is formed. If $50\text{ mL}$ of $O_2$ is used instead, with $100\text{ mL}$ of $N_2$, the volume of $NO$ formed will be:

Which of the following statements about the Law of Multiple Proportions is FALSE?

According to Dalton, an atom of Oxygen is different from an atom of Nitrogen primarily because of its:

Which of the following is a key feature of atoms as described by Dalton?

According to Dalton, all matter—whether an element, a compound, or a mixture—is composed of:

Dalton's atomic theory was based on the concept of 'atomos' which was first suggested by:

Dalton's theory could not explain the difference between which of the following pairs?

If an atom of element X has a mass of $10$ units and an atom of element Y has a mass of $20$ units, according to Dalton, what would be the mass of a 'compound atom' $XY_2$?

What did Dalton believe was the result of a chemical reaction?

Dalton's Atomic Theory provided a theoretical justification for which of the following laws that were already known at the time?

If we could split an atom of Oxygen in a chemical laboratory using standard reagents, which Daltonian principle would be directly invalidated?

What was the most significant flaw in Dalton's postulate regarding the 'simplest ratio' in compounds?

What is the molecular mass of Phosphoric acid ($H_{3}PO_{4}$)? (Atomic masses: $H = 1.0\ u, P = 31.0\ u, O = 16.0\ u$)

Determine the formula mass of Potassium Carbonate ($K_{2}CO_{3}$). (Atomic masses: $K = 39.0\ u, C = 12.0\ u, O = 16.0\ u$)

What is the atomic mass of Calcium ($Ca$)?

Calculate the molecular mass of Methanol ($CH_{3}OH$). (Atomic masses: $C = 12.0\ u, H = 1.0\ u, O = 16.0\ u$)

Calculate the molecular mass of Methanol ($CH_3OH$). (Atomic masses: $C = 12, H = 1, O = 16$)

An atom is 16 times as heavy as 1/12th of the mass of a Carbon-12 atom. What is its atomic mass?

What is the mass of one atom of Carbon-12 in grams?

If the mass of $10^{22}$ atoms of an element is $0.93\ g$, what is the atomic mass of the element?

Based on the elemental analysis ratio shown, if the mass ratio of $C:H$ in a compound is $6:1$ and its vapor density is $14$, what is the molecular formula?

A compound with molar mass $160$ contains $35\%$ Chromium and $40\%$ Iron by mass. How many atoms of Iron are there per molecule of the compound? (At mass $Fe=56, Cr=52, O=16$)

Which of the following is equal to the Avogadro constant?

Calculate the molar mass of Nitric Acid ($HNO_{3}$). ($H = 1, N = 14, O = 16$)

How many moles of $O_{2}$ contain $1.2044 \times 10^{24}$ molecules?

What is the mass of 1.5 moles of $CO_{2}$?

Calculate the mass of a single atom of Carbon-12.

The number of grams of $H_{2}SO_{4}$ present in 0.1 moles of $H_{2}SO_{4}$ is:

How many moles of Phosphoric acid ($H_{3}PO_{4}$) contain 0.25 moles of oxygen atoms?

A $2.43\ g$ sample of magnesium ribbon is burned in a limited supply of air to form a mixture of magnesium oxide ($MgO$) and magnesium nitride ($Mg_{3}N_{2}$). The resulting residue is treated with excess water to convert the nitride into magnesium hydroxide and ammonia gas. If $0.17\ g$ of $NH_{3}$ gas is evolved, what is the mass percentage of the original magnesium that was converted into the nitride form? (Atomic masses: $Mg = 24.3$, $N = 14.0$, $H = 1.0$)

In the industrial Contact Process, sulfuric acid is produced through a sequence of steps. Starting with the roasting of iron pyrites:

1. $4FeS_{2} + 11O_{2} \rightarrow 2Fe_{2}O_{3} + 8SO_{2}$
2. $2SO_{2} + O_{2} \rightarrow 2SO_{3}$
3. $SO_{3} + H_{2}O \rightarrow H_{2}SO_{4}$

If $240\ g$ of iron pyrites ($FeS_{2}$) is roasted and the overall efficiency of the final step (conversion of $SO_{3}$ to $H_{2}SO_{4}$) is only $80\%$, while the previous steps have $100\%$ yield, what mass of $H_{2}SO_{4}$ is produced? (Molar masses: $FeS_{2} = 120\ g/mol$, $H_{2}SO_{4} = 98\ g/mol$)

If the molecular mass of a compound is $90$ and its empirical formula is $CHO_{2}$, what is its molecular formula?

If a compound has a molar mass of $100$ g/mol and contains $40$ g of element $X$, what is the mass percentage of $X$?

What is the mass percentage of Oxygen in acetic acid ($CH_3COOH$)? (Molar mass = $60$ g/mol, $O = 16$)

What is the mass percentage of Hydrogen in acetic acid ($CH_3COOH$)? (Molar mass = $60$ g/mol, $H = 1$)

Calculate the mass percentage of Carbon in acetic acid ($CH_3COOH$). (Molar mass = $60$ g/mol, $C = 12$)

In Silver Bromide ($AgBr$), determine the mass percentage of Bromine. (Atomic masses: $Ag=108, Br=80$)

A sample of a mineral contains $10$ g of pure $CaCO_3$ in a total mass of $12.5$ g. What is the percentage purity of the mineral with respect to $CaCO_3$?

Calculate the mass percentage of Iron in Green Vitriol ($FeSO_4 \cdot 7H_2O$). (Atomic masses: $Fe=56, S=32, O=16, H=1$)

Analysis of a compound shows it contains $20\%$ Calcium and $80\%$ Bromine by mass. What is the empirical formula weight?

A compound contains $28\%$ Iron and $72\%$ Chlorine by mass. The empirical formula of the compound is: (At. mass $Fe=56, Cl=35.5$)

Which of the following has the highest mass percentage of Nitrogen?

How many grams of $CO_2$ are contained in 11.2 L of the gas at STP (1 atm)?

The ratio of the mass of a product obtained to the mass expected from the balanced equation is related to:

What is the molarity of a solution containing 4 g of $NaOH$ in 1 L of solution?

In the reaction $N_2 + 3H_2 \rightarrow 2NH_3$, if 14 g of $N_2$ is used, how many grams of $H_2$ are needed? (N=14, H=1)

If 1.5 moles of $CuCl_2$ reacts with 2 moles of $NaOH$, what is the maximum number of moles of $Cu(OH)_2$ that can be formed?

What volume of Water Gas (equal parts $CO$ and $H_2$) is produced by passing steam over 24 g of red hot Carbon? ($C + H_2O \rightarrow CO + H_2$)

A mixture of $CO$ and $CO_2$ has a volume of 50 mL. On passing over heated charcoal, the volume becomes 70 mL. What was the original volume of $CO_2$ in the mixture?

0.1 mole of $MnO_4^-$ is reduced to $Mn^{2+}$. The number of Faradays required for this reduction is:

A mixture of $KBr$ and $NaBr$ weighing 0.560 g was treated with aqueous $AgNO_3$ and all the bromide ion was recovered as 0.970 g of $AgBr$. What was the fraction of $KBr$ in the original sample?

What is the molar volume of an ideal gas at 273.15 K and 1 bar pressure? (Note: Standard condition defined by IUPAC)

Which of the following temperatures is the same on both Celsius and Fahrenheit scales?

What is the unit of density in the SI system?

Which of the following is a heterogeneous mixture?

The prefix 'mega' represents which multiple?

The SI unit for time is based on which of the following?

A piece of wood floats on water because its density is less than $1.0\text{ g/cm}^3$. If a block of wood has dimensions $2\text{ cm} \times 5\text{ cm} \times 10\text{ cm}$ and a mass of $80\text{ g}$, what is its density?

How many significant figures are in the measurement $6.002$?

Perform the operation $1.2 \times 10^{-3} - 5.0 \times 10^{-4}$ and report with correct significant figures.

Which temperature is physically impossible?

The volume of a substance is $20.0\ cm^3$ and its mass is $40.00\ g$. The density should be reported as:

How many significant figures are in the measurement $4.50 \times 10^3$?

Which of these represents a volume of $1 \text{ dm}^3$?

What is the density of a substance if its mass is $10.0 \text{ g}$ and volume is $2.0 \text{ mL}$? (Use significant figures)

If a measurement is $10.5 \text{ g} \pm 0.1 \text{ g}$, what is the uncertainty?

An analytical chemist needs to convert a liquid volume of $0.250$ $L$ into cubic meters ($m^3$) for a density calculation. Using the conversion logic shown in the diagram and given that $1$ $m^3 = 1000$ $L$, what is the value expressed in scientific notation with the correct number of significant figures?

A laboratory calculation requires the following operation: $\frac{0.024 + 1.20}{0.120}$. Following the rules for uncertainty in measurement and significant figures, which of the following is the correctly reported result?

What is the value of $0.02 + 0.002$ reported correctly?

The prefix 'pico' represents which factor in scientific notation?

A sample of $0.00200$ moles of a substance is dissolved in $10.0$ mL of water. What is the concentration in mol/L with correct sig figs?

Solve: $5.67 \times 10^8 - 4.2 \times 10^7$ with correct sig figs.