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Problems

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276 problems
Type:
1.
0.50 kg of water at 75 °C is poured into 1.5 kg of water at 15 °C in an insulated jug.
High School (11–12) · Heat Engines, the Second Law and EntropyStemPy LabStemPy Lab
Hard
2.
On the Pauling scale sodium is 0.9, hydrogen 2.1, carbon 2.5 and chlorine 3.0. New
High School (11–12) · Periodic Trends, Groups and FamiliesStemPy LabStemPy Lab
Hard
3.
The rungs of a ladder are 20 cm apart. Their lengths fall evenly from 50 cm at the bottom to 30 cm… New
High School (9–10), General · Sequences and SeriesStemPy LabStemPy Lab
Hard
4.
In a district, there were 10 000 boys under six in both of two surveys. New
High School (9–10), General · Human ReproductionStemPy LabStemPy Lab
Hard
5.
From gallium to krypton the first ionisation enthalpies are 579, 762, 947, 941, 1140 and 1351… New
High School (11–12), High School (9–10), Undergraduate, General · Chemistry by Computer, Data Analysis with pandasStemPy LabStemPy Lab
Hard
6.
Find the mean temperature of the first 10 days and of the last 10 days.
Middle Stage (6–8), High School (9–10), High School (11–12), Undergraduate, General · Averages: Mean, Median and Mode, Spread of Data, Probability and ChanceStemPy LabStemPy Lab
Hard
7.
A Carnot engine works between 880 K and 286 K and gives out 12 kW of mechanical power.
High School (11–12) · Heat Engines, the Second Law and EntropyStemPy LabStemPy Lab
Hard
8.
The electron gain enthalpy of chlorine is -349 kJ mol⁻¹ and that of fluorine -328 kJ mol⁻¹. New
High School (11–12) · Periodic TrendsStemPy LabStemPy Lab
Hard
9.
How many terms of 21, 18, 15, … must be added to get 81? Explain why there are two answers. New
High School (9–10), General · Sequences and SeriesStemPy LabStemPy Lab
Hard
10.
Put these events in the right order, and explain the link between the second and the third: the… New
High School (9–10), General · Reproduction in PlantsStemPy LabStemPy Lab
Hard
11.
25 mL of 0.05 mol/L sulphuric acid is titrated with 0.1 mol/L sodium hydroxide: H₂SO₄ + 2NaOH →… New
High School (11–12), High School (9–10), Undergraduate, General · Chemistry by ComputerStemPy LabStemPy Lab
Hard
12.
The 10 rainy days had a total of 285 °C, and the 20 dry days a total of 637 °C.
Middle Stage (6–8), High School (9–10), High School (11–12), Undergraduate, General · Averages: Mean, Median and Mode, Spread of Data, Probability and ChanceStemPy LabStemPy Lab
Hard
13.
A gas with γ = 1.40 at 5.5 × 10⁵ Pa fills 1.2 litres.
High School (11–12) · Thermodynamic Processes and Specific Heats of GasesStemPy LabStemPy Lab
Hard
14.
Suppose only the two 1s electrons shield the outer electrons of period 2, so S = 2. New
High School (11–12) · Periodic TrendsStemPy LabStemPy Lab
Hard
15.
The sum of the first n terms of an arithmetic progression is 4n² - n. New
High School (9–10), General · Sequences and SeriesStemPy LabStemPy Lab
Hard
16.
In an aquarium, a Hydra makes one bud every 4 days. New
High School (9–10), General · Reproduction in PlantsStemPy LabStemPy Lab
Hard
17.
Zinc reacts with excess hydrochloric acid: Zn + 2HCl → ZnCl₂ + H₂. New
High School (11–12), High School (9–10), Undergraduate, General · Chemistry by ComputerStemPy LabStemPy Lab
Hard
18.
The chance of a rainy day is 1/3. If the days did not affect each other, what would be the chance…
Middle Stage (6–8), High School (9–10), High School (11–12), Undergraduate, General · Averages: Mean, Median and Mode, Spread of Data, Probability and ChanceStemPy LabStemPy Lab
Hard
19.
0.80 mol of a monatomic ideal gas goes from A to C in two steps.
High School (11–12) · Thermodynamic Processes and Specific Heats of GasesStemPy LabStemPy Lab
Hard
20.
A lanthanoid has the configuration [Xe] 4f⁷ 6s². New
High School (11–12) · Development of the Periodic Table, Groups and FamiliesStemPy LabStemPy Lab
Hard
21.
How many three-digit numbers are multiples of 9? New
High School (9–10), General · Sequences and SeriesStemPy LabStemPy Lab
Hard
22.
In a moss, a fern and a pine, say which generation is the main plant, and whether the other… New
High School (11–12) · Plant Life Cycles and Alternation of Generations, Gymnosperms and AngiospermsStemPy LabStemPy Lab
Hard
23.
Boyle's law says that for a gas at a fixed temperature, the pressure is inversely proportional to…
High School (11–12), High School (9–10), Undergraduate, General · Data Analysis with pandasStemPy LabStemPy Lab
Hard
24.
The second week of the month, days 8 to 14, had the highest temperatures 29, 28, 30, 32, 33, 35, 34…
Middle Stage (6–8), High School (9–10), High School (11–12), Undergraduate, General · Averages: Mean, Median and Mode, Spread of Data, Probability and ChanceStemPy LabStemPy Lab
Hard
25.
A gas goes clockwise round a triangle ABCA on a pressure-volume graph.
High School (11–12) · Laws of ThermodynamicsStemPy LabStemPy Lab
Hard
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