What does chemistry study in material substances?
Preparation, properties, structure, and reactions.
During which years did chemistry develop mainly as Alchemy and Iatrochemistry?
1300–1600 CE.
When did modern chemistry take shape in Europe?
In the eighteenth century.
What were the ancient Indian names for chemistry?
Rasayan Shastra, Rastantra, Ras Kriya, and Rasvidya.
What materials did Harappans produce using metallurgy?
Baked and glazed pottery, faience, and objects from lead, silver, gold, and copper.
How did Harappans increase the hardness of copper?
By adding tin and arsenic.
Where and when were ancient Indian glass objects found?
At Maski (1000–900 BCE) and Hastinapur and Taxila (1000–200 BCE).
What does Kautilya’s Arthashastra describe about salt production?
Producing salt from the sea.
What did Acharya Kanda propose about the nature of substances?
They consist of eternal, indestructible, spherical, indivisible particles called Paramãnu.
What does Nagarjuna’s Rasratnakar discuss?
Mercury compounds and methods for extracting gold, silver, tin, and copper.
What medicinal use does Charaka Samhita describe related to metal bhasmas?
Their extreme particle-size reduction linked to nanotechnology involving metal nanoparticles.
What defines matter in chemistry?
Anything that has mass and occupies space.
Name one area where chemistry contributes to food production.
Chemistry contributes to fertilisers.
Which drugs are effective in cancer therapy?
Cisplatin and taxol.
What is AZT used for?
To help AIDS patients.
What materials has chemistry enabled by designing specific properties?
Superconducting ceramics, conducting polymers, and optical fibres.
What environmental issue do chlorofluorocarbons contribute to?
Stratospheric ozone depletion.
What has been done to chlorofluorocarbons to reduce their harm?
Safer alternatives have been synthesised.
Which gases remain concerns for greenhouse effects?
Methane and carbon dioxide.
How is matter classified macroscopically?
Into mixtures and pure substances.
Into which categories are pure substances further classified?
Elements and compounds.
What defines a homogeneous mixture?
Components are uniformly distributed with uniform composition.
What characterizes a heterogeneous mixture?
Non-uniform composition with visible different components.
How can mixture components be separated?
By physical methods like hand-picking, filtration, crystallisation, and distillation.
What is an element?
A pure substance with only one type of atom in its particles.
What defines a compound?
Atoms of different elements combined in a definite ratio.
How can compounds be separated into simpler substances?
Only by chemical methods.
What distinguishes physical properties from chemical properties?
Physical properties can be measured without changing a substance's identity.
What does a quantitative observation include?
A number followed by the unit of measurement.
When was the International System of Units established?
In 1960 by the 11th General Conference on Weights and Measures.
What are the seven SI base quantities?
Length, mass, time, electric current, thermodynamic temperature, amount of substance, luminous intensity.
What is the formula for density in terms of mass and volume?
Density equals mass divided by volume, ρ = m/V.
What is the SI unit of density?
Kilogram per cubic meter (kg·m⁻³).
How are Celsius and Fahrenheit temperature scales related?
Fahrenheit equals nine-fifths Celsius plus 32, F = 9/5 C + 32.
How are Kelvin and Celsius temperature scales related?
Kelvin equals Celsius plus 273.15, K = °C + 273.15.
What does one mole contain exactly?
Exactly 6.02214076×10²³ specified elementary entities.
What is the Avogadro constant expressed in mol⁻¹?
6.02214076×10²³ elementary entities per mole.
What is the difference between mass and weight?
Mass is constant amount of matter; weight is gravitational force and varies by location.
How is a number represented in scientific notation?
As N times 10 to the power n, where N is between 1.000 and 9.999 and n is an integer.
Which digits are always significant in a number?
All non-zero digits are significant.
Are zeros before the first non-zero digit significant?
No, zeros before the first non-zero digit are not significant.
What defines precision in measurements?
Precision is how close repeated measurements are to each other.
What defines accuracy in measurements?
Accuracy is how close a measurement is to the true value.
How many decimal places can the result have in addition or subtraction?
No more decimal places than the least precise original number.
How many significant figures can the result have in multiplication or division?
No more significant figures than the factor with the fewest significant figures.
How does dimensional analysis convert units?
By multiplying by unit factors equal to one.
What is the key step in selecting unit factors in dimensional analysis?
Choosing factors that produce the desired units.
How are units cancelled in dimensional analysis?
By algebraic cancellation of units.
What length in centimeters equals 3 inches using 1 in = 2.54 cm?
7.62 cm.
How many seconds are in 2 days using standard time conversions?
172800 seconds.
What does the law of conservation of mass state about matter?
Matter can neither be created nor destroyed during changes.
What does the law of definite proportions say about a compound's element ratios?
A compound always contains the same elements in the same mass proportions.
What percentages of copper, carbon, and oxygen are in cupric carbonate?
51.35% copper, 9.74% carbon, and 38.91% oxygen by mass.
What does the law of multiple proportions state about element mass ratios?
Masses of one element combine with fixed mass of another in small whole-number ratios.
What is the oxygen mass ratio in water and hydrogen peroxide from 2 g hydrogen?
The oxygen masses are in a 1:2 ratio.
What does Gay-Lussac’s law of gaseous volumes state about reacting gases?
Gases combine in simple whole-number volume ratios at the same temperature and pressure.
What volume ratio do hydrogen, oxygen, and water vapor have at the same temperature and pressure?
The volume ratio is 2:1:2 for hydrogen, oxygen, and water vapor.
What does Avogadro’s law state about equal gas volumes at the same conditions?
Equal volumes contain equal numbers of molecules at the same temperature and pressure.
What does Dalton's atomic theory say about the nature of matter?
Matter consists of indivisible atoms.
According to Dalton, how do atoms of the same element compare?
They have identical properties and mass.
How do atoms of different elements differ in Dalton's theory?
They differ in mass.
How are compounds formed according to Dalton's atomic theory?
By fixed-ratio combination of atoms.
What happens to atoms during chemical reactions in Dalton's theory?
Atoms are reorganized without being created or destroyed.
When did John Dalton publish A New System of Chemical Philosophy?
In 1808.
What chemical laws did Dalton's atomic theory explain?
The laws of chemical combination.
What could Dalton's atomic theory not explain?
The laws of gaseous volumes and why atoms combine.
What is one atomic mass unit defined as?
One atomic mass unit is one-twelfth the mass of a carbon-12 atom.
What exact mass is assigned to carbon-12?
Carbon-12 is assigned an exact mass of 12 u.
In which year was the atomic-mass standard agreed upon?
The atomic-mass standard was agreed upon in 1961.
What is the mass of one atomic mass unit in grams?
One atomic mass unit equals 1.66056 × 10⁻²⁴ grams.
What is the approximate atomic mass of a hydrogen atom?
The mass of a hydrogen atom is approximately 1.008 u.
What does average atomic mass represent?
Average atomic mass is the weighted mean of an element’s isotopes’ masses.
What is the formula for molecular mass?
Molecular mass is M = Σ n_i A_i, summing atoms times atomic masses.
What is formula mass?
Formula mass is the sum of atomic masses in a formula unit without discrete molecules.
What is the mole in the SI system?
The SI unit of amount of substance.
How many elementary entities does one mole contain?
Exactly 6.02214076 × 10²³ entities.
What is the value of the Avogadro constant N_A?
6.02214076 × 10²³ mol⁻¹.
What does molar mass represent?
The mass of one mole of a substance.
In what units is molar mass expressed?
Grams per mole.
How does molar mass relate numerically to atomic or molecular mass?
It equals the atomic, molecular, or formula mass in atomic mass units.
How many entities are in one mole regardless of the substance?
6.022 × 10²³ entities.
Test your knowledge with 48 questions on Basic Concepts of Chemistry.
1. What does chemistry primarily study?
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