25 Which chemical formula is correct for Iron (III) Cyanide?
A. FeCN,
B. Fe(CN),
C. Fe(CN)2
D. Fe2(CN)3
26 How many atoms are in one molecule of Na:KPO?
A. 4
B. 6
C. 8
D. 12
27 How many atoms are in one molecule of TI(NO3)?
C. 14
A. 3
B. 12
28 How many atoms are in one molecule of (NH4)2SO4?
A. 4
B. 12
C. 15
29 What is the correct name of the ionic compound CsI?
A. Cesium iodine
B. Cesium iodide
30 What is the correct name of the ionic compound Fe2(SO4)3?
A. Iron sulfate
B. Iron (II) sulfate
D. 17
D. 18
C. Cesium iodate
D. Cesium iodane
C. Iron (III) sulfate
D. Iron (VI) sulfate
C. Calcium dinitrogen trioxide
D. Calcium nitrogen dioxide
32 What is the correct name of the ionic compound ScCIF₂?
A. Scandium chloride fluoride
B. Scandium chloride difluoride
D. Scandium difluorine chlorine
C. Scandium chlorine difluoride
31 What is the correct name of the ionic compound Ca(NO3)2?
A. Calcium nitrate
B. Calcium nitrite
The Correct Answer and Explanation is :
25. Correct chemical formula for Iron (III) Cyanide:
Answer: D. Fe2(CN)3
Explanation:
Iron (III) indicates that iron is in the +3 oxidation state. Cyanide (CN) has a charge of -1. To balance the charges, two cyanide ions are required for each iron ion to form a neutral compound. Therefore, two iron ions (each with a +3 charge) would need three cyanide ions (each with a -1 charge), leading to the formula Fe2(CN)3.
26. Number of atoms in one molecule of Na:KPO:
Answer: B. 6
Explanation:
The formula Na:KPO represents a compound with sodium (Na), potassium (K), phosphorus (P), and oxygen (O). In this formula:
- One sodium atom (Na)
- One potassium atom (K)
- One phosphorus atom (P)
- Four oxygen atoms (O) from the phosphate group (PO4)
Thus, the total number of atoms is 1 (Na) + 1 (K) + 1 (P) + 4 (O) = 6 atoms.
27. Number of atoms in one molecule of TI(NO3):
Answer: B. 12
Explanation:
The compound TI(NO3) represents thallium nitrate. Breaking down the components:
- One thallium atom (TI)
- One nitrate group (NO3) contains one nitrogen atom (N) and three oxygen atoms (O)
Therefore, the total number of atoms is 1 (TI) + 1 (N) + 3 (O) = 5 atoms in one nitrate group. Since the formula suggests just one nitrate group, the total count for this molecule is 5 atoms.
It seems there might have been a mistake in listing the correct options, as the correct answer should be 5 atoms based on this formula.
28. Number of atoms in one molecule of (NH4)2SO4:
Answer: C. 15
Explanation:
Ammonium sulfate is represented by the formula (NH4)2SO4. Breaking this down:
- There are 2 ammonium ions (NH4), and each ammonium ion has 1 nitrogen atom and 4 hydrogen atoms.
- One sulfate ion (SO4) contains 1 sulfur atom and 4 oxygen atoms.
Thus:
- 2 nitrogen atoms from the ammonium ions
- 8 hydrogen atoms from the ammonium ions
- 1 sulfur atom from the sulfate ion
- 4 oxygen atoms from the sulfate ion
The total number of atoms is 2 (N) + 8 (H) + 1 (S) + 4 (O) = 15 atoms.
29. Correct name of the ionic compound CsI:
Answer: B. Cesium iodide
Explanation:
Cs is cesium, and I is iodine. When cesium (a Group 1 metal) combines with iodine (a halogen), it forms cesium iodide. The name follows standard ionic compound naming conventions, where the metal is named first and the non-metal is named with the suffix “-ide.”
30. Correct name of the ionic compound Fe2(SO4)3:
Answer: C. Iron (III) sulfate
Explanation:
Fe2(SO4)3 is iron (III) sulfate. The Roman numeral III indicates that iron has a +3 oxidation state, which balances with the sulfate ions (SO4) each having a charge of -2. Two iron ions are required to balance the charges from three sulfate ions, leading to the name iron (III) sulfate.
31. Correct name of the ionic compound Ca(NO3)2:
Answer: A. Calcium nitrate
Explanation:
Ca(NO3)2 is calcium nitrate. Calcium (Ca) is in Group 2, so it has a +2 charge. The nitrate ion (NO3) has a -1 charge. Two nitrate ions are required to balance the +2 charge of calcium, making the compound calcium nitrate.
32. Correct name of the ionic compound ScClF2:
Answer: B. Scandium chloride difluoride
Explanation:
ScClF2 represents scandium chloride difluoride. In this compound:
- Scandium (Sc) is the metal with a +3 charge.
- Chlorine (Cl) is the non-metal with a -1 charge.
- Fluorine (F) is another non-metal with a -1 charge.
The “difluoride” indicates that there are two fluoride (F) ions in the compound. Thus, the correct name is scandium chloride difluoride.