Science and Technology MCQ Set 58
Showing question 286 to 290 of total 301 MCQs
MCQ Set: 58
Solve the question on your notebook and check it by clicking (Answer and Explanation) below question.
Question No: 286
MHA minister Shri Rajnath Singh launched which web portal and mobile app for donors to contribute to the family of Indian soldiers?
- Bharat Ke Veer
- Bharat Ke Rakshak
- Bharat Ke Sena
- Bharat Ki Roshni
Answer and Explanation
Answer: A
Explanation
Union Home Minister Shri Rajnath Singh launched the web portal and mobile application named “Bharat ke Veer”.
The portal is an IT based platform, with an objective to enable willing donors to contribute towards the family of a braveheart who sacrificed his/her life in line of duty.
The Minister of State for Home Affairs Shri Kiren Rijiju and actor Akshay Kumar also participated.
The site “Bharat ke Veer” will be available on web portal as well as mobile application.
The amount so donated will be credited to the account of ‘Next of Kin’ of those Central Armed Police Force/Central Para Military Force soldiers.
This domain allows anyone to financially support the bravehearts of his/her choice or towards the “Bharat Ke Veer” corpus.
This website is technically supported by National Informatics Centre (NIC) and powered by SBI.
To ensure maximum coverage, a cap of 15 lakh rupees is imposed and the donors would be alerted if the amount exceeds, so that they can choose to divert part of the donation to another braveheart account or to the “Bharat Ke Veer” corpus.
“Bharat Ke Veer” corpus would be managed by a committee made up of eminent persons of repute and senior Government officials, who would decide to disburse the fund equitably to the braveheart’s family on need basis.
Question No: 287
What is a self healing material which can stretch up to 50 times its original size, developed by UCLA researchers, made of?
- Stretchable polymer
- Stretchable jute
- Ionic sat
- Only a and c
- All the above
Answer and Explanation
Answer: D
Explanation
Phones with cracked screens is a common sight these days and scientists at University of California have come up with a method to solve this problem.
They have successfully created a self-healing material which when carved into two parts, can go back together like nothing has happened.
The material is a made up of stretchable polymer and an ionic salt.
It can stretch up to 50 times its original size also capable of conducting electricity.
All these features combined make it a viable material for producing smartphones screen.
The substance has potential applications in the field of soft robotics as well.
The polymer is based on the premise that materials consist of a mix of strong covalent bonds and weaker non-covalent bonds.
When a material gets damaged, non-covalent bonds protect covalent bonds by getting broken first.
As weak as these non-covalent bonds are, however, they’re also reversible, which means after they’re broken, they can also recover. And this cycle can be repeated over and over again.
The properties are attributed to a specific kind of bond called ion dipole interaction, basically force between ions and molecules.
What happens is that when the two ends of the broken material meet, this force causes the ions and molecules to get attracted to each other.
The ion-dipole interaction causes the broken non-covalent bonds to reunite and reform, resulting in the material healing its own damage.
The research team's inspiration for self-healing material was comes from Marvel superhero Wolverine!
Question No: 288
What unique property does the zigzag edge of a graphene layer have?
- It allows flow of charge without resistance at room temperature
- It allows flow of charge without resistance at more than room temperature
- It allows flow of charge without resistance at less than room temperature
- Both a and b
- All of the above
Answer and Explanation
Answer: D
Explanation
Researchers from the Indian Institute of Science (IISc), Bengaluru have been able to experimentally produce a new type of electrical conductor that was theoretically predicted nearly 20 years ago.
The team produced graphene that is single- or a few-layers thick to conduct current along one particular edge — the zigzag edge.
The zigzag edge of graphene layer has a unique property: It allows flow of charge without any resistance at room temperature and above.
This is the first time one has found the perfect edge structure in graphene and demonstrated electrical conductance along the edge.
A few-layers-thick graphene that conducts current along one edge does not experience any resistance and so can lead to realising power-efficient electronics and quantum information transfer, even at room temperature.
Many groups over the world have been trying to access these edges since the emergence of graphene in 2004, but have been largely unsuccessful because when current flows through graphene, it flows through both the edge as well as the bulk.
By creating the bulk part of graphene extremely narrow (less than 10 nanometre thick), and hence highly resistive, thus forcing the current to flow through the edge alone, IISc scientists have overcome this block.
While the bulk is totally insulating, the edge alone has the ability to conduct because of the unique quantum mechanics of the edge.
As the zigzag orientation of carbon atoms [resulting from the hexagonal lattice], the electron wave on each carbon atom overlaps and forms a continuous train of wave along the edge.
This makes the edge conducting, even if it is very long but has to be chemically and structurally pristine.
In the past, others researchers had tried making narrow graphene through chemical methods.
But the use of chemicals destroys the edges. So the IISc team resorted to mechanical exfoliation to make graphene that are single- and few-layers thick.
There are currently several chemical methods to produce very narrow graphene nanoribbons. But these chemicals tend to destroy the edges.
So the challenge is to produce graphene nanoribbons using chemicals that do not destroy the edges.
This innovation makes high-quality graphene nano-ribbons or nano-strips with clean edges possible.
Question No: 289
Which type of high power batteries for e-vehicles and automobiles have been indigenously developed by ISRO?
- Carbon
- Lithium ion
- Nickel Cadmium
- Lead Acid
Answer and Explanation
Answer: B
Explanation
The government has asked Indian Space Research Organisation (ISRO) to allow manufacturers interested in producing indigenous lithium-ion batteries.
This is including those from private sector, to obtain the technology for its mass production.
ISRO will now come up with a framework to make this process smooth.
The Vikram Sarabhai Space Centre under ISRO has developed indigenous technology to manufacture such high-power batteries for automobiles and e-vehicles and their feasibility tests in vehicles have been successful.
Over half a dozen major automobile companies, battery manufacturers and public sector undertakings have already approached ISRO.
This include Mahindra Renault, Hyundai, Nissan, Tata Motors, High Energy Batteries, BHEL and Indian Oil.
The aim is to develop indigenous technology for lithium-ion batteries so that their prices are within the reach of Indian customers.
ISRO had earlier developed similar batteries for satellite and the launch vehicle applications.
The government has set an ambitious target for pushing more use of electric vehicles to reduce air pollution, which has become one of the biggest health concerns.
Batteries are the key component of any electric vehicle.
At present, all lithium-ion batteries are imported and it's very expensive.
Such batteries have high-power, but these weigh less and their volume is much less as well in comparison to conventional batteries.
Government documents show the cost of lithium-ion batteries is high because of small volume of procurement.
Bulk procurement and mass production can reduce the cost by 80%, which is key to push demand.
Lithium Ion Batteries: Know More
Specific energy: 100–265 W·h/kg (0.36–0.875 MJ/kg)
Energy density: 250–676 W·h/L (0.90–2.43 MJ/L)
Specific power: ~250-~340 W/kg
Charge/discharge efficiency: 80–90%
Self-discharge rate per month: 8% at 21 °C/15% at 40 °C/31% at 60 °C
Cycle durability:400–1200 cycles
Nominal cell voltage: NMC 3.6 / 3.85 V, LiFePO4 3.2 V
A lithium-ion battery or Li-ion battery (abbreviated as LIB) is a type of rechargeable battery.
Question No: 290
Which element has been used to make a sieve to separate salt from sea water?
- Graphene
- Carbon
- Hydrogen
- Helium
Answer and Explanation
Answer: A
Explanation
Researchers have developed a graphene-based sieve capable of removing salt from seawater, an advance that may provide clean drinking water for millions of people.
When immersed in water, graphene-oxide membranes become slightly swollen and smaller salts flow through the membrane along with water, while larger ions or molecules are blocked.
Researchers have now successfully developed graphene membranes and found a strategy to avoid the swelling of the membrane when exposed to water.
The pore size in the membrane can be precisely controlled, which can sieve common salts out of salty water and make it safe to drink.
When the common salts are dissolved in water, they always form a ‘shell’ of water molecules around the salt molecules.
This allows the tiny capillaries of the graphene-oxide membranes to block the salt from flowing along with the water.
Water molecules are able to pass through the membrane barrier and flow anomalously fast which is ideal for application of these membranes for desalination, researchers said.
Realisation of scalable membranes with uniform pore size down to atomic scale is a significant step forward and will open new possibilities for improving the efficiency of desalination technology according to Professor Rahul Nair, University of Manchester.
The membranes are not only useful for desalination, but the atomic scale tunability of the pore size also opens new opportunity to fabricate membranes with on-demand filtration capable of filtering out ions according to their sizes.