Which element is placed at the top of the electrochemical series?
Copper
Hydrogen
Sodium
Oxygen
Correct answer is C
In the electrochemical series, also known as the reactivity series, Sodium is placed at the top. The electrochemical series is a list of elements in the order of their standard electrode potentials (or redox potentials). Elements at the top of the series are more reactive and have a greater tendency to lose electrons and form positive ions.
The same number of protons but different numbers of neutrons.
The same number of neutrons and electrons
The same number of protons and neutrons
The same number of protons and electrons
Correct answer is A
Isotopes of an element have the same number of protons (which defines the element) but may have different numbers of neutrons. Since atoms are electrically neutral, the number of protons must equal the number of electrons in an atom.
Tetrahedral
Trigonal planar
Linear
Octahedral
Correct answer is B
In a molecule with three bonding pairs and no lone pairs around the central atom, the electron pairs arrange themselves in a trigonal planar geometry, with bond angles of approximately 120 degrees.
At room temperature and standard pressure, chlorine gas is in which state of matter?
Plasma
Solid
Liquid
Gas
Correct answer is D
Chlorine gas exists in the gaseous state at room temperature (around 25 degrees Celsius) and standard pressure.
Sodium reacts vigorously with water to produce
Sodium chloride (NaCl) and oxygen gas (O2)
Sodium nitrate (NaNO3) and water (H2O)
Sodium hydroxide (NaOH) and hydrogen gas (H2)
Sodium oxide (Na2O) and hydrogen gas (H2)
Correct answer is C
When sodium reacts with water, it undergoes a highly exothermic reaction, producing sodium hydroxide (NaOH) and hydrogen gas (H2).