Question 3 :
Which of the following is not an allotropic form of carbon?
Question 4 :
What is the smallest part of the crystal that has the three-dimensional pattern of the whole lattice called?
Question 5 : <div><span>The phenomenon of existence of an element in more than one physical form is called allotropy.</span><br/></div>
Question 6 :
What is the smallest part of the crystal that has the three-dimensional pattern of the whole lattice called?
Question 7 :
Fullerene, an allotrope of carbon, has 60 carbon atoms joined together and no other element in it. There are various types of fullerenes. $C_{60}, C_{70}, C_{74}$ and $C_{78}$ are the members of the fullerene family. Identify the property due to which such large numbers of carbon atoms are joined together in this molecule<span> :</span>
Question 9 :
If X is a non-metal, it will not conduct electricity unless it is carbon in the form of __________.
Question 12 :
A non-metal $X$ exists in two different forms $Y$ and $Z$. $Y$ is the hardest natural substance whereas $Z$ is a good conductor of electricity. $Y$ is :<br/>
Question 13 :
Which of the following compounds would be a white, crystalline solid?
Question 15 :
Compounds with identical crystal structure and analogous chemical formula are called:
Question 16 :
The carbon atoms in diamond are bonded to each other by:
Question 19 :
If X is a non-metal. It will not conduct electricity unless it is carbon in the form of :<br/>
Question 22 :
Which of the following statements is/are incorrect for diamond?<br/>(a) The refractive index of diamond is highest among solids.<br/>(b) Diamond is hard because all the valence electrons of each carbon atom are involved in bond formation.<br/>(c) Diamond is thermodynamically more stable than graphite.<br/>(d) <span>One carat of diamond represents its weight.</span>
Question 25 :
Which of the following compounds would be a white, crystalline solid?
Question 28 :
In which of the given pairs the two compounds are allotropes of the same element?
Question 29 :
An allotropic form of carbon used for cutting and drilling is which of the following?
Question 30 :
Graphite is a soft solid lubricant extremly difficult to melt. The reason for this anomalous behaviour is that graphite<span> :</span>
Question 31 :
Which of the following substances are crystalline allotrope of carbon?<br/>(i) Diamond (ii) Charcoal (iii) Graphite (iv) Lamp black (v) Coke (vi) Fullerene
Question 32 :
Some elements show the property of existing in two or more distinct physical form which shows different physical properties but same chemical properties. These distinct forms of an element are called:
Question 39 :
Which of the following is not a use of graphite ?
Question 40 :
Two adjacent layers in graphite are bonded by comparatively _______ forces.<br/>
Question 42 :
The most common fullerene is $C_{60}$. 60 C-atoms are arranged in ______ pentagons and ______ hexagons.<br/>
Question 43 :
Graphite is used as a lubricant in machines because it has a very high melting point and also it :
Question 44 :
Fullerene is an allotrope of carbon which is similar to a football. It has 60 carbon atoms joined together and no other element in it. There are various types of fullerenes. $C_{60}, C_{70}, C_{74}$ and $C_{75}$ are the members of the fullerene family. But $C_{60}$ (pronounced as C sixty) is the most stable and most studied form of fullerenes. What do you think is the nature of the bond which is joining these atoms together?
Question 47 :
Due to the weak Van der Waals' forces and less distance between the layers, graphite :
Question 50 : Which of the following statement is true for graphite?<div><br/>(a) In graphite, each carbon atom is bonded to four other carbon atoms.<br/>(b) Graphite is very hard.<br/>(c) It is a good conductor of electricity.<br/>(d) It is bad conductor of electricity.</div>
Question 52 :
Graphite is a ______ conductor of electricity whereas diamond is a ______ conductor of electricity.
Question 53 : (i) It is used in making leads of pencils.<br/>(ii) It is used as dry lubricant.<br/>(iii) It is used in making black paint and printers ink.<br/>(iv) It is used in nuclear reactors as moderator.<div><br/>Which is this substance?</div>
Question 55 :
Which of the following allotropes of carbon is isomorphous with crystalline silicon?
Question 56 : The following characteristics of a substance are given.<div>What is the name of this substance?<div><br/></div><div>(i) It is used as an abrasive for cutting glass.<div><br/>(ii) It is used as a tip of deep boring drills.</div><div><br/>(iii) It is used for making dies for drawing wires.</div><div><br/>(iv) It is used in generating laser beams in electronics.</div></div></div>
Question 57 :
Which of the following can conduct electricity in the solid state ?
Question 58 : <p>Which of the following element's allotrop is the primary absorber of UV solar radiation in Earth's atmosphere ?</p>
Question 61 :
The number of free electrons in the outermost shell of carbon in graphite is:
Question 62 :
Assertion: Diamond and graphite are allotropes of carbon
Reason: Some elements can have several different structural forms while in the same physical state. These differing forms are called allotropes.
Question 63 :
Some elements show the property of existing in two or more distinct physical form which show different physical properties but same chemical properties. These distinct forms of an element are called :
Question 65 :
A crystalline solid is made of two atoms X and Y. Atoms of 'X' are present at the corner while atoms of 'Y' are present at face centres. If one atom of 'X' is missing from the corner, then the simplest formula of the solid is:
Question 66 :
The allotrope of carbon which is a good conductor of heat and electricity is:
Question 67 :
Crystalline form of carbon having 60 carbon atoms joined together is called :
Question 68 :
An allotropic form of carbon used for cutting and drilling is :
Question 71 :
Some solid crystalline compounds slowly change to the gaseous state when left at room temperature in an open container. Which of the following is true about this phenomenon?
Question 77 :
Which of the following can conduct electricity in a fused state?
Question 78 :
Assertion: Crystalline solids can cause X-rays to diffract.
Reason: Interatomic distance in crystalline solids is of the order of $0.1$ nm.
Question 79 :
Which of the following compounds represents an inverse $2 : 3$ spinel structure?
Question 81 :
Assertion: Crystalline solids can cause X-rays to diffract.
Reason: Interatomic distance in crystalline solids is of the order of $0.1$ nm.
Question 83 :
Assertion: Glass belongs to the category of ionic solid.
Reason: Glass is supercooled liquid.
Question 86 : <div><b>Statement-I: </b>Initially the term pseudo solid was given for solids which were easily distorted by bending and compressing forces. They even tend to flow slowly under its own weight and lose shape.<div><br/><b>Statement-II:</b> These characteristics are shown by pseudo solids as in pitch, glass and thus, the name pseudo solid was replaced by supercooled liquids.<br/></div></div>
Question 87 :
The melting point of RbBr is $682^\circ C$, while that of NaF is $988^\circ C$. The principal reason that melting point of $NaF$ is much higher than that of $RbBr$ is that :
Question 89 :
Gas equation $pV = nRT$ is obeyed by ideal gas in
Question 92 :
The melting point of RbBr is $682^\circ C$, while that of NaF is $988^\circ C$. The principal reason that melting point of $NaF$ is much higher than that of $RbBr$ is that :
Question 93 :
Which of the following can conduct electricity in a fused state?
