General
✓✗Diamond is very hard because
- it is an ionic solid
- each C atom is covalently bonded to four others in a rigid three-dimensional network
- its layers slide over one another
- it contains delocalised electrons
General
✓✗Which of the following tetrahalides does not undergo hydrolysis in water under ordinary conditions?
- CCl4
- GeCl4
- SiCl4
- SnCl4
General
✓✗Carbon and silicon belong to group 14. The maximum coordination number of carbon in commonly occurring compounds is 4, whereas that of silicon is 6. This is due to
- both the large size and the more electropositive nature of silicon
- the more electropositive nature of silicon
- the large size of silicon
- the availability of low-lying d orbitals in silicon
General
✓✗Which of the following statements about the anomalous behaviour of carbon is correct?
- Carbon can expand its octet using d orbitals
- Carbon shows a maximum covalency of 6
- Carbon can form pπ−pπ multiple bonds with itself and with N and O
- Carbon has the largest atomic size in group 14
General
✓✗Boron differs from the other members of group 13 mainly because of its
- metallic nature
- small size, high ionisation enthalpy and absence of d orbitals
- low electronegativity
- large size
General
✓✗In one layer of graphite, each carbon atom forms how many σ bonds and contributes how many electrons to the delocalised π system?
- 4 σ bonds and 0 electrons
- 3 σ bonds and 2 electrons
- 3 σ bonds and 1 electron
- 2 σ bonds and 2 electrons
General
✓✗The C−C bond length in diamond is 154 pm and the interlayer distance in graphite is 340 pm. The large interlayer distance shows that
- graphite is ionic
- graphite has a three-dimensional network like diamond
- the layers in graphite are held together by weak van der Waals forces
- graphite layers are covalently bonded
General
✓✗Germanium is classified as
- a typical non-metal
- a typical metal
- a noble gas
- a metalloid
General
✓✗Which of the following is an insulator?
- Aluminium
- Diamond
- Graphite
- Silicon
General
✓✗The common oxidation states shown by group 14 elements are
- +5 and +3
- +3 and +1
- +4 and +2
- +6 and +4
General
✓✗Which of the following statements about the trends in group 13 is incorrect?
- Metallic character increases from B to Al
- Ionisation enthalpy does not decrease regularly down the group
- The +1 state becomes more stable down the group
- Atomic radius increases regularly from B to Tl without exception
General
✓✗Assertion: Carbon shows a maximum covalency of 4.
Reason: Carbon has vacant d orbitals in its valence shell.
Reason: Carbon has vacant d orbitals in its valence shell.
- Both Assertion and Reason are true and Reason is the correct explanation of Assertion
- Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
- Assertion is true but Reason is false
- Both Assertion and Reason are false
General
✓✗In the p-block elements, the last electron enters the
- s orbital
- p orbital
- d orbital
- f orbital
General
✓✗The tendency of BF3, BCl3 and BBr3 to behave as Lewis acids decreases in the sequence
- BF3 > BCl3 > BBr3
- BCl3 > BF3 > BBr3
- BBr3 > BF3 > BCl3
- BBr3 > BCl3 > BF3
General
✓✗Why is the reactivity of aluminium in air very low in practice even though it is a reactive metal?
- A thin, adherent and impervious layer of Al2O3 protects the metal
- Aluminium is below hydrogen in the series
- Aluminium does not combine with oxygen
- Aluminium has a very high ionisation enthalpy