Egyptian STEM Schools Admissions Assessment · STEM Sciences

Physical Sciences and Chemical Systems

81 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 81 questions

  1. A solid wooden cube of side and density floats in pure water (density ). What depth of the cube is submerged beneath the water surface?
  2. What is the balanced stoichiometric coefficient of when propane () undergoes complete combustion to produce carbon dioxide and water: ?
  3. A cart of mass traveling at collides with a stationary cart of mass . If they couple together after the collision, what is their combined velocity?
  4. Which type of chemical bond is formed when two atoms share valence electrons equally due to identical or negligible electronegativity difference?
  5. An electric circuit contains three resistors of resistances , and connected in parallel across a battery. What is the total equivalent resistance of the…
  6. What is the molar mass of sulfuric acid ()? (Atomic masses: )
  7. A ball is thrown vertically upward with an initial velocity of . Assuming and negligible air resistance, what maximum height does it reach?
  8. Which of the following elements has the highest first ionization energy?
  9. An object is placed in front of a concave mirror with a focal length of . Where is the image formed?
  10. According to Boyle's law, what happens to the volume of an ideal gas when its pressure is tripled at constant temperature?
  11. A runner accelerates uniformly from rest to a speed of in . What total distance did the runner cover during this acceleration?
  12. What is the oxidation state of sulfur in the sulfate ion ()?
  13. Which electromagnetic radiation has higher frequency and shorter wavelength than visible light, but lower frequency than X-rays?
  14. What is the concentration in molarity (M) of a solution prepared by dissolving of sodium hydroxide () in water to make of solution? (Molar mass of…
  15. Two point charges of and are separated by a distance . If the separation distance is doubled to , what happens to the electrostatic repulsive force between t…
  16. Which gas law explains why an inflated balloon placed in liquid nitrogen shrinks dramatically in volume?
  17. What type of chemical reaction is represented by where oxygen is simultaneously oxidized and reduced?
  18. A force of is applied at an angle of to the horizontal to pull a crate across a flat floor over a distance of . How much work is done by the applied force? (…
  19. Which subatomic particle was discovered by J.J. Thomson using cathode ray tube experiments, establishing that atoms are divisible?
  20. A sound wave travels from air into water. What happens to its speed, frequency, and wavelength?
  21. What is the conjugate base of the bisulfate ion () according to Bronsted-Lowry acid-base theory?
  22. A light ray in glass () strikes the interface with air (). What is the critical angle for total internal reflection? ()
  23. Which of the following is an intensive thermodynamic property that does NOT depend on the quantity of matter in a system?
  24. What is the kinetic energy of a projectile moving at a velocity of ?
  25. Which periodic trend correctly explains why atomic radius decreases from left to right across Period 3 of the periodic table?
  26. If the half-life of a radioactive isotope is 10 days, what fraction of the original sample remains after 30 days?
  27. A heat engine operates between and . If it absorbs of heat from the hot reservoir, what is the theoretical maximum work it can produce?
  28. A projectile is launched with velocity at an angle above horizontal (take ). What is its maximum he…
  29. In an electrochemical cell, what is the standard Gibbs free energy change for a reaction with moles of electrons and ? (…
  30. What is the pH of a solution of ammonium chloride ()? ()
  31. Two sound waves of frequencies and interfere. What is the beat frequency and the period between successive maximum intensities?
  32. A motor lifts a load with a force of 50 N through 5 m in 2 s. What power does it develop?
  33. Which test shows that a hydrocarbon is an alkene?
  34. A force of 50 N moves an object 3 m in the direction of the force. How much work is done?
  35. What resultant force gives a 7 kg mass an acceleration of 7 m/s²?
  36. What mass of NaCl is needed to make 0.5 L of a 2 mol/L solution? (Relative atomic masses: Na = 23, Cl = 35.5.)
  37. How many moles are there in 294 g of H₂SO₄? (Relative atomic masses: H = 1, S = 32, O = 16.)
  38. What is the oxidation number of P in H₃PO₄?
  39. A block has mass 54 g and volume 20 cm³. What is its density?
  40. At 25 °C a solution has pH 5. What is its pOH?
  41. A body with initial speed 5 m/s accelerates at 6 m/s² over 12 m. What is its final speed?
  42. A wave has frequency 20 Hz and wavelength 0.5 m. What is its speed?
  43. A spring of constant 800 N/m is stretched by 0.2 m. What energy is stored in it?
  44. What is the mass of 5 mol of Fe₂O₃? (Relative atomic masses: Fe = 56, O = 16.)
  45. An atom has atomic number 16. How many electrons are in its outer shell?
  46. A 1 kg object moving at 8 m/s is brought to rest. How much kinetic energy does it lose?
  47. A force of 50 N moves an object 5 m in the direction of the force. How much work is done?
  48. The fundamental frequency of a string is 5 Hz. What is the frequency of its fourth harmonic?
  49. What is the effect of a catalyst on a reaction?
  50. Sound travels at 30 m/s. What is the wavelength of a note of frequency 10 Hz?
  51. 20 mL of a 12 mol/L solution is diluted to 0.5 mol/L. What is the final volume?
  52. Three resistors of 27 Ω, 2 Ω and 4 Ω are in series. What is the total resistance?
  53. How many protons are in ?
  54. In , what mass of water forms from 4 g of hydrogen with excess oxygen? (H = 1, O = 16)
  55. How many neutrons are in ?
  56. An object is 30 cm from a converging lens of focal length 20 cm. How far from the lens is the image?
  57. What is the mass of 0.5 mol of HCl? (Relative atomic masses: H = 1, Cl = 35.5.)
  58. A compound contains 36 g carbon, 6 g hydrogen and 32 g oxygen. What is its empirical formula? (C = 12, H = 1, O = 16)
  59. Heating gives . What volume of at STP comes from 250 g of ? (Ca = 40, C = 12, O = 16; molar volume 22.4 L/mol)
  60. What is the oxidation number of S in SO₂?
  61. 25 mL of 0.2 mol/L HCl is neutralised by 0.1 mol/L NaOH. What volume of NaOH is needed?
  62. A gas has volume 6 L at 327 °C. At constant pressure it is heated to 27 °C. What is its new volume?
  63. What is the oxidation number of Cl in HClO₄?
  64. A body moving at 3 m/s accelerates uniformly at 3 m/s² for 8 s. What is its final speed?
  65. What does the law of conservation of energy state?
  66. A force of 10 N moves an object 5 m in the direction of the force. How much work is done?
  67. A 500 kg car moving at 10 m/s is stopped by a constant braking force of 2500 N. What is the stopping distance?
  68. What is the oxidation number of Fe in Fe₂O₃?
  69. An appliance on a 12 V supply draws 2 A. What is its power?
  70. For , how many moles of water form from 6 mol and 5 mol ?
  71. Three resistors of 9 Ω, 17 Ω and 21 Ω are in series. What is the total resistance?
  72. A radioactive sample has 800 undecayed nuclei. How many remain after 3 half-lives?
  73. How many protons are in ?
  74. A cell of emf 12 V and internal resistance 1 Ω drives a 4 Ω resistor. What is the current?
  75. A wave has frequency 200 Hz and wavelength 4 m. What is its speed?
  76. How much energy is needed to raise the temperature of 2 kg of water by 13 °C? (Specific heat capacity of water J/(kg·°C).)
  77. 25 mL of a 6 mol/L solution is diluted to 0.1 mol/L. What is the final volume?
  78. A spring of constant 50 N/m is stretched by 0.1 m. What energy is stored in it?
  79. Which process separates crude oil into fractions?
  80. What volume does 1 mol of any gas occupy at STP? (Molar volume 22.4 L/mol)
  81. A ball is kicked at 10 m/s at to level ground. What is its range? (Use m/s², ignore air resistance.)

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