A) big bang nucleosynthesis B) triple- alpha process C) CNO Cycle D) r-process
A) when the star has used up all its hydrogen fuel B) when the star has burned all its oxygen C) when the silicon fusion stops D) when the chromium fusion stops
A) Hydrogen fusion stops, and the pressure in the core decreases. B) Nuclear energy increases until carbon and helium burning occur C) Gravity squeezes the star until helium and hydrogen burning occur. D) Hydrogen fusion continues, and the pressure in the core increases.
A) The big bang nucleosynthesis formed the light elements (H, He, and Li). B) Stellar formation and evolution formed their elements from Be to Fe. C) Stellar explosion, or supernova, formed the elements heavier the Fe. D) Stellar evolution formed no elements at all.
A) 75 B) 261 C) 186 D) 111
A) Zn-58 B) Ni-58 C) Cu-58 D) Ni-59
A) Julius Lothar Meyer B) John Newlands C) Henry Moseley D) Dmitri Mendeleev
A) Rn-211 B) At-212 C) At-210 D) Po-211
A) All of these B) Atomic number is the number of protons, the atoms are arranged by the increasing number of protons C) Atomic number is the number of electrons, the atoms are arranged by the decreasing number of protons D) Atomic number is the number of neutrons, the atoms are arranged by the increasing number of protons
A) Stellar Nucleosynthesis B) R-Process C) Primordial Nucleosynthesis D) Supernova Nucleosynthesis
A) valence electrons B) positron C) electrons in fully occupied orbitals D) stable inner electrons
A) metallic bond B) electrostatic bond C) ionic bond D) covalent bond
A) PF3 B) IF5 C) CO2 D) I2
A) It has zero net dipole moment B) It is a polar molecule C) It has both polar and nonpolar covalent bonds D) It has one ionic bond
A) Br—Br B) Li—Br C) Se—Br D) Na—Cl
A) All bonds are polar covalent B) There is lone pair in the central atom and arranged unevenly that cause the dipole moment C) Polar bonds are arranged such that they cancel each other D) There is a polar bond present
A) To produce an aromatic solution B) To speed up the chemical reaction without being consumed in the process C) To bridge the difference in polarity of two or more substances D) To make the other substance polar
A) A molecule is polar B) A molecule is water-loving C) A molecule is water-fearing D) Molecules of a substance is uniformly distributed in water solvent
A) The molecule has two poles, at which it is colder than other regions of the molecule. B) The equal sharing of electrons gives the water molecule a slight negative charge near its oxygen atom and a slight positive charge near its hydrogen atoms C) The water molecule is neutral. D) The unequal sharing of electrons gives the water molecule a slight negative charge near its hydrogen atoms and a slight positive charge near its oxygen atom |