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The source of biodiesel is from plant parts. During the growth and development of these plants, they absorb carbon dioxide from the environment for photosynthesis. During the combustion of biodiesel, the same amount of carbon dioxide is released to the environment.
The net amount of carbon added to the environment from the burning of biodiesel is considered to be zero, hence “carbon neutral”.
The atoms of Group O elements have a stable electronic configuration, hence these atoms have no tendency to gain or lose electrons to form ions, making them chemically inert.
Initially, the car’s speed is increasing. This causes the frictional forces to increase. With the forward driving force remaining constant, the resultant force acting on the car will be decreasing.
Since resultant force = mass x acceleration, with a decreasing resultant force, and constant mass, acceleration will be decreasing. This is represented by the decreasing gradient of the speed-time graph.
Eventually, the forward driving force will be equal to frictional forces. When this happens, resultant force acting on the car will be zero, so acceleration will be zero, and the car will be moving at constant speed. This is represented by the horizontal portion of the speed-time graph.
A live wire carries a high voltage and carries current from the electrical plug to the appliance.
The switch connected to the live wire will ensure that the appliance is at zero voltage every time the appliance is switched off, making the appliance safer to use.
The fuse connected to the live wire will ensure that high current flow to the appliance will immediately be cut off, preventing damage to the wirings and appliance due to the high current flow.
This appliance is missing an earth wire, but it most likely has double insulation.
Appliances with double insulation have their internal parts and wirings completely insulated from the outer casing, and the outer casing will be made of an electrical insulator, eg plastic.
This means that, even if a live wire touches the casing, it will not become “live”, hence it will be safe to use even without an earth wire.
Note: Appliances with double insulation will have this symbol:
The short answer is no.
The insulator can be charged via electrostatic charging by friction, but not by electrostatic charging by induction. The charges do not travel easily from the insulator to the conductor or vice versa, simply by putting them in contact.
The electrons in the insulator are not delocalised, hence they are not able to move freely within its own body or cross over to another body to induce a charge.
Examples:
Answer is A
Answer is D
Pure metals consist of a lattice of positive ions, arranged in regular pattern, surrounded by a sea of delocalised electrons. When a force is applied, the layers of positive ions slide over one another easily, without disrupting the metallic bonding. This makes the pure metal soft and malleable.
An alloy is a mixture of a pure metal with other elements. The atoms of the added element have a different size from those of the pure metal. This breaks up the regular arrangement of atoms in the pure metal. When a force is applied, the atoms of different sizes cannot slide over one another easily. This makes the alloy stronger and harder.
In an empty room, the hard and solid walls, floors and ceilings act as good reflectors of sound, so the sound waves reflect repeatedly off these surfaces, creating echo.
In a fully furnished room, there are usually soft, hollow surfaces, like the fabric sofa; the thick curtains; the wardrobe, etc, that act as good absorbers of sound. This reduces the effect of echo.
At the start, the gradient of the curve is the steepest. This shows that speed of reaction is the highest at the start. The concentration of the reacting particles is the highest at the start, resulting in highest speed of reaction.
As the reaction progresses, the gradient of the curve decreases. This shows that speed of reaction is slowing down. As the reactants are used up in the reaction, the concentration of reacting particles decreases, resulting in a decrease in speed of reaction.
When the gradient of the curve becomes horizontal, it shows that the reaction has stopped. Either one or all of the reactants have been completely used up, so reaction stopped.
In a storm cloud, water droplets are brought upwards in an updraft within the storm clouds. The droplets cool and freeze into hail and smaller ice particles as they rise upwards. The heavier hail particles that formed then fall back downwards, rubbing against the rising small ice particles.
Electrostatic charging by friction occurs, with the hail particles gaining electrons from the small ice particles. The heavier hail particles, which have become negatively charged, gathered at the bottom part of the storm clouds, while the lighter small ice particles, which have become positively charged, gathered at the top part of the storm clouds.
Electrons near the ground are repelled by the negatively charged bottom of the storm clouds, moving deeper into the ground, resulting in the objects on the surface of the ground becoming positively charged. As the negative charges build up at the bottom of the clouds, surrounding air particles are ionised, sending stepped leaders towards the ground. At the same time, the positively charged objects on the ground also ionise the air particles around them, sending streamers upwards towards the clouds.
When a particular stepped leader and streamer meet, a path is established, and the huge potential difference between the cloud and the object results in a massive current flow.
This huge current flow produces an enormous amount of heat, up to 30 000 deg C, which appear to us as the brilliant white-blue flash of a lightning flash.