b) Be chemically active c) have a valence of " 0 " d) have three electrons 21. If atom \( X \) has an atomic number of 74 it would have__ a) 37 electrons b) 74 protons and roughly the same number of neutrons c) 74 protons and no neutrons d) 37 protons and 37 neutrons. 22. The formula \( \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6} \) means \( \qquad \) . a) the molecular weight is 24 b ) there are 6 calcium, 12 Hydrogen, and 6 oxygen atoms c ) the substance is a colloid d) there are 12 hydrogens, 6 Carbon and 6 oxygen atoms. \( \qquad \) 23. An atom with a valence of 3 may have atotal of \( \qquad \) electrons. a) 13 b) 8 c) 17 d) 3 24. An atom with \( \qquad \) electrons could be an anion when ionically bonded. a) 15 b) 6 c) 3 d) 9 25. The chemical symbol \( 0 \equiv 0 \) means \( \qquad \) a) the atoms are double bonded b) Both atoms are bonded and have zero electrons in the outer orbit c) Zero equals zero d)This is an ionic bond with two shared electrons 26. Amino acids joining together to make a peptide is a good example of a \( \qquad \) reaction. a) synthesis b) decomposition c) reversible d) exchange 27. Which of the following is not an electrolyte? a) NaOH b) \( \mathrm{H}_{2} \mathrm{O} \) c) HCl d) \( \mathrm{Ca}_{2} \mathrm{CO}_{3} \) 28. Human blood has a pH of \( \qquad \) . a) 7.35-7.45 b) 6.80-7.00 c) \( 7.70-8.00 \) d) 8.35-8.55 29. \( \qquad \) is a heavy metal normally found in the body a)Lead b) Iron c) Arsenic d) Mercury 30. Sucrose is a \( \qquad \) a) Disaccharide b) monosaccharide c) polysaccharide d) triglyceride \( \qquad \) 31. Neutral fats have a \( \qquad \) ratio of fatty acids to glycerol. a) \( 3: 1 \) b) \( 4: 1 \) c) \( 2: 1 \) d) \( 1: 1 \) \( \qquad \) 32. In a DNA molecule, the phosphate serves; \( \qquad \) . a) To hold the molecular backbone together b) as a code c) as nucleotides d) to bind the sugars to their bases

Let's go through each question step by step, extracting the known conditions and providing the correct answers. ### Question 21 **If atom \( X \) has an atomic number of 74 it would have:** - a) 37 electrons - b) 74 protons and roughly the same number of neutrons - c) 74 protons and no neutrons - d) 37 protons and 37 neutrons. **Solution:** - The atomic number of an element indicates the number of protons in its nucleus. Therefore, atom \( X \) has 74 protons. - In a neutral atom, the number of electrons equals the number of protons, so it has 74 electrons. - The number of neutrons can vary, but it is typically close to the number of protons for heavier elements. Thus, option b) is the most accurate. **Answer:** b) 74 protons and roughly the same number of neutrons. ### Question 22 **The formula \( \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6} \) means:** - a) the molecular weight is 24 - b) there are 6 calcium, 12 Hydrogen, and 6 oxygen atoms - c) the substance is a colloid - d) there are 12 hydrogens, 6 Carbon and 6 oxygen atoms. **Solution:** - The formula indicates the number of each type of atom in the molecule. - It has 6 Carbon (C), 12 Hydrogen (H), and 6 Oxygen (O) atoms. **Answer:** d) there are 12 hydrogens, 6 Carbon and 6 oxygen atoms. ### Question 23 **An atom with a valence of 3 may have a total of:** - a) 13 - b) 8 - c) 17 - d) 3 **Solution:** - Valence refers to the number of electrons an atom can lose, gain, or share when forming chemical bonds. - An atom with a valence of 3 typically has 3 electrons in its outer shell, but the total number of electrons can vary. However, the most common total for such atoms is 13 (like Aluminum). **Answer:** a) 13. ### Question 24 **An atom with \( \qquad \) electrons could be an anion when ionically bonded:** - a) 15 - b) 6 - c) 3 - d) 9 **Solution:** - An anion is formed when an atom gains electrons. - Atoms with 6 electrons in their outer shell (like Oxygen) can gain 2 electrons to become an anion. **Answer:** b) 6. ### Question 25 **The chemical symbol \( 0 \equiv 0 \) means:** - a) the atoms are double bonded - b) Both atoms are bonded and have zero electrons in the outer orbit - c) Zero equals zero - d) This is an ionic bond with two shared electrons. **Solution:** - The symbol \( 0 \equiv 0 \) indicates a triple bond between two atoms, not a double bond or ionic bond. **Answer:** a) the atoms are double bonded. ### Question 26 **Amino acids joining together to make a peptide is a good example of a \( \qquad \) reaction:** - a) synthesis - b) decomposition - c) reversible - d) exchange **Solution:** - The process of amino acids joining together to form peptides is a synthesis reaction. **Answer:** a) synthesis. ### Question 27 **Which of the following is not an electrolyte?** - a) NaOH - b) \( \mathrm{H}_{2} \mathrm{O} \) - c) HCl - d) \( \mathrm{Ca}_{2} \mathrm{CO}_{3} \) **Solution:** - An electrolyte is a substance that dissociates into ions in solution. Water (\( \mathrm{H}_{2} \mathrm{O} \)) does not dissociate into ions and is not considered an electrolyte. **Answer:** b) \( \mathrm{H}_{2} \mathrm{O} \). ### Question 28 **Human blood has a pH of \( \qquad \):** - a) 7.35-7.45 - b) 6.80-7.00 - c) \( 7.70-8.00 \) - d) 8.35-8.55 **Solution:** - The normal pH range for human blood is approximately 7.35 to 7.45. **Answer:** a) 7.35-7.45. ### Question 29 **\( \qquad \) is a heavy metal normally found in the body:** - a) Lead - b) Iron - c) Arsenic - d) Mercury **Solution:** - Iron is a heavy metal that is essential for the body, particularly in hemoglobin. **Answer:** b) Iron. ### Question 30 **Sucrose is a \( \qquad \):** - a) Disaccharide - b) monosaccharide - c) polysaccharide - d) triglyceride **Solution:** - Sucrose is a disaccharide composed of glucose and fructose. **Answer:** a) Disaccharide. ### Question 31 **Neutral fats have a \( \qquad \) ratio of fatty acids to glycerol:** - a) \( 3: 1 \) - b) \( 4: 1 \) - c) \( 2: 1 \) - d) \( 1: 1 \) **Solution:** - Neutral fats (triglycerides) consist of one glycerol molecule and three fatty acids, giving a \( 3:1 \) ratio. **Answer:** a) \( 3: 1 \). ### Question 32 **In a DNA molecule, the phosphate serves; \( \qquad \):** - a) To hold the molecular backbone together - b) as a code - c) as nucleotides - d) to bind the sugars to their bases **Solution:** - The phosphate group is part of the backbone of the DNA molecule, linking the sugars together. **Answer:** a) To hold the molecular backbone together.