IdeasCuriosas - Every Question Deserves an Answer Logo

Questions in chemistry

[Answered] Which of the following statements is true of the critical temperature of a pure substance? A. The critical temperature is the temperature above which the liquid phase of a pure substance can exist. B. The critical temperature is the temperature above which the liquid phase of a pure substance cannot exist. C. The critical temperature is the temperature below which the liquid phase of a pure substance cannot exist. D. The critical temperature is the temperature at which all three phases can coexist. E. The critical temperature is the temperature at which the pure substance reaches, but cannot go beyond, the critical pressure.

[Answered] Salt water is classified as a 1. compound because the proportion of its atoms is fixed 2. compound because the proportion of its atoms can vary 3. mixture because the proportion of its components is fixed 4. mixture because the proportion of its components can vary

[Answered] What is the approximate mass of a proton? (1) 1 u (2) 0.0005 u (3) 1 g (4) 0.0005 g

[Answered] An electron in a sodium atom gains enough energy to move from the second shell to the third shell. The sodium atom becomes: 1. a positive ion 2. a negative ion 3. an atom in an excited state 4. an atom in the ground state

[Answered] Which quantity represents the number of protons in an atom? (a) atomic number (b) oxidation number (c) number of neutrons (d) number of valence electrons

[Answered] The elements in Group 2 have similar chemical properties because each atom of these elements has the same: (a) atomic number (b) mass number (c) number of electron shells (d) number of valence electrons

[Answered] When an atom of the unstable isotope Na-24 decays, it becomes an atom of Mg-24 because the Na-24 atom spontaneously releases: 1. an alpha particle 2. a beta particle 3. a neutron 4. a positron

[Answered] How many formula units of [tex]$NaNO_3$[/tex] are in 5.23 moles of [tex]$NaNO_3$[/tex] (Mw. 85.00 g/mol)?

[Answered] After decaying for 48 hours, 1/16 of the original mass of a radioisotope sample remains unchanged. What is the half-life of this radioisotope?

[Answered] What is formed when two atoms of bromine bond together? 1. a monatomic molecule 2. a diatomic molecule 3. a heterogeneous mixture 4. a homogeneous mixture Gold can be flattened into an extremely thin sheet. The malleability of gold is due to the 1. radioactive decay mode of the isotope Au-198 2. proton-to-neutron ratio in an atom of gold 3. nature of the bonds between gold atoms 4. reactivity of gold atoms