Semmelweis Entrance Exam Chemistry| Questions With Verified Answers

Semmelweis Entrance Exam Chemistry| Questions With Verified Answers What are the 4 main elements of living organisms? Correct Answer: carbon, nitrogen, oxygen, hydrogen What are atomic orbitals? Correct Answer: regions where there is a high probability of finding an electron What are the first few electron configurations? Correct Answer: 1s 2s, 2p 3s, 3p, 3d 4s, 4p, 4d, 4f What are primary chemical bonds? Correct Answer: ionic, covalent, metallic What are secondary chemical bonds? Correct Answer: 1. Hydrogen bonds 2. Van der Waals bonds What are hydrogen bonds? Correct Answer: Bonds between hydrogen atom and atoms of the most electronegative elements (N, O, F) What are Van der Waal's bonds? Correct Answer: The first type is a result of electrostatic attraction between two permanent dipoles The second type of Van der Waal's bond is formed due to temporary dipoles Properties of water Correct Answer: • strong hydrogen bonds • high heat capacity • solvent • needs a lot of energy to evaporate • expands when freezes • cohesion (sticks to itself) • adhesion (sticks to other things) What are the intermolecular forces in water? Correct Answer: Hydrogen bonds, dipole-induced dipole forces, and London dispersion forces Ionization of water Correct Answer: the transfer of a proton from one water molecule to another to produce a hydroxide ion and a hydronium ion What are the types of concentrations? Correct Answer: mass concentration, molar concentration, number concentration, and volume concentration. What is the definition of pH? Correct Answer: measure of hydrogen ion concentration of a solution to determine acidity/basic What is the formula for pH? Correct Answer: pH = -log[H+] What is chemical equilibrium? Correct Answer: the rate of the forward reaction is equal to the rate of the reverse reaction What is le chatelier's principal? Correct Answer: If a stress occurs in a reaction, the equilibrium will shift to counter the stress What is an exothermic reaction? Correct Answer: a reaction that transfers energy to its surroundings (solution becomes colder) What is an endothermic reaction? Correct Answer: A reaction that ABSORBS energy in the form of heat (solution becomes hotter) What is the conservation of energy? Correct Answer: Energy cannot be created or destroyed, only transferred What is enthalpy? Correct Answer: total heat content of a system (H)