Which metal forms compounds that can be used to colour glass?
A) aluminium
B) calcium
C) chromium
D) sodium
▶️ Answer/Explanation
Ans: C
Transition metal compounds are commonly used to color glass due to their colorful ions:
- Aluminium (A): Compounds are generally colorless in glass.
- Calcium (B): Used to make glass but doesn’t provide color.
- Chromium (C): Correct answer. Chromium compounds produce different colors:
- Chromium(III) oxide (Cr2O3) – green
- Potassium dichromate (K2Cr2O7) – orange
- Sodium (D): Used in glass manufacturing but doesn’t provide color.
Chromium is a transition metal whose compounds are well-known for their use in coloring glass and ceramics.
Question
The table gives some properties of an element.
Which other property does this element have?
A. acts as a catalyst
B. brittle
C. forms an acidic oxide
D. highly reactive with water
▶️Answer/Explanation
Ans:
A
Molybdenum itself is a silvery-grey metal, similar in appearance to other transition metals.
Molybdenum chloride exists in different oxidation states, resulting in different chloride compounds. One example is Molybdenum(IV) chloride (MoCl4), which is a dark blue compound.
Molybdenum compounds, including molybdenum chloride, can act as catalysts in various chemical reactions. They are particularly useful in catalyzing reactions involving carbon-carbon bond formation, such as olefin metathesis and hydrodesulfurization. The high melting point you mentioned, 3422°C, is a characteristic property of molybdenum itself, rather than its chloride compounds.
Question
The properties of the element titanium, Ti, can be predicted from its position in the Periodic Table. Which row identifies the properties of titanium?
▶️Answer/Explanation
Ans:B
Titanium can be used as a catalyst in various chemical reactions. Titanium-based catalysts find applications in several industrial processes and organic transformations.
Being a transition metal, titanium tends to have a relatively high density and melting point.
Titanium is a transition metal, which generally exhibits metallic properties such as high thermal and electrical conductivity, malleability, and ductility.
Titanium, a transition metal is known for forming colored compounds. The presence of different oxidation states and coordination environments in titanium compounds contributes to their vibrant colors.
Question
An element melts at \(1455^o\)C, has a density of 8.90 g / \(cm^3\) and forms a green chloride.
Where in the Periodic Table is this element found?
▶️Answer/Explanation
Ans: C
Its high melting point, high density and colored chloride properties indicate that it is a transition element. It is C.