Answer:
Explanation:
Melting and boiling point variations are not clear (do not have uniform pattern) in periodic table. But we can see, some elements have higher melting and boiling points and some have less. Here we study melting and boiling points of s, p, d blocks elements. IVAth group elements (C,Si) show high melting and boiling points because they have covalent gigantic lattice structures.
The answer is: 60.
Tobacco products are made up of thousands of chemicals, including at least 60 known to cause cancer (carcinogens).
Some of carcinogens chemicals are: acetaldehyde, arsenic, radioactive elements (for example polonium-210), nitrosamines, nickel, benzene, polycyclic aromatic hydrocarbons, vinyl chloride.
Smoking tobacco causes at least 15 different types of cancer. For example: mouth, pharynx, larynx, oesophagus, liver, pancreas, stomach, kidney cancer.
Following is the balanced <span>radioactive decay series:
</span><span>
Particle/radiations generated during the reaction are labeled in bold at end of reaction.
Care must be taken that, atomic number and atomic mass number should be balanced in each of these reactions.
1) 92 238U </span>→ <span> 90 234Th + 2 4He(</span>α particle<span>)
A = </span>90 234Th because alpha particle is emitted along with it. So atomic number of daughter element has to be 92 - 2 = 90. This corresponds to Th. <span>
2) 90 234Th </span>→<span> 91 234Pa + -1 0e (electron)
B = -1 0e i.e electron because after radioactive disintegration atomic number of daughter element (Pa) is +1 as compared to parent element (Th)
3) 91 234Pa </span>→<span> 92 234U + –1 0e (electron)
</span>C = 92 234U because electron is emitted along with it. So atomic number of daughter element has to be 91 - (-1) = 92. This corresponds to U. <span>
4) 92 234U </span>→ 90 230Th + 2 4He (α particle<span>)
</span><span>In this case, 92 234U undergoes nuclear disintegration to generate 90 230Th and alpha particle
5) 90 230Th </span>→<span> 88 226Ra + 2 4He </span>(α particle)
D = 88 226Ra because alpha particle is emitted along with it. So atomic number of daughter element has to be 90 - 2 = 88. This corresponds to Ra.
<span>6) 88 266Ra </span>→ 86 222Rn + 2 4He (α particle)
E = alpha particle because during nuclear disintegration, 88 266Ra is converted into 86 222Rn. Hence, for mass balance we have 88 - 86 = 2. It corresponds to alpha particles.
<span>
7) 86 222Rn </span>→<span> 84 218Po + 2 4He </span>(α particle)
Again, F = alpha particle because during nuclear disintegration, 86 222Rn is converted into 84 218Rn. Hence, for mass balance we have 86 - 84 = 2. It corresponds to alpha particles.
<span>
8) 84 218Po </span>→<span> 82 214Pb + 2 4He </span>(α particle)
G = 82 214Pb because alpha particle is emitted along with it. So atomic number of daughter element has to be 84 - 2 = 82. This corresponds to Pb.
<span>
9) 82 214Pb </span>→<span> 83 214Bi + -1 0e (electron)
H = </span>-1 0e because after radioactive disintegration atomic number of daughter element (Bi) is +1 as compared to parent element (Pb)<span>
10) 83 214Bi </span>→<span> 84 214Po + –1 0e (electron)
I = </span>84 214Po because electron is emitted along with it. So atomic number of daughter element has to be 83 - (-1) = 84. This corresponds to Po.<span>
11) 84 214Po </span>→<span> 82 210Pb + 2 4He </span>(α particle)
J = 82 210Pb because alpha particle is emitted along with it. So atomic number of daughter element has to be 84 - 2 = 82. This corresponds to Pb.
The correct answer is From different social and ethnic backgrounds.
Explanation:
The purpose of science studies is to gain an understanding of specific phenomena and use this in the benefit of the world or humanity. Moreover, science is guided by objective methods and these are applied all around the world. This feature allows scientists from all kinds of social and ethnic backgrounds to study the same phenomena and obtain similar results, which is essential for the progress of scientific knowledge. This is exemplified by two different labs in two different countries studying drug absorption because the results of these two studies can be analyzed together to understand drug absorption.
In this context, one factor that contributes to the progress of scientific knowledge is the effort of scientists "from different social and ethnic backgrounds".
Answer:
Explanation:
1. Given that,
Initial speed of a bicycle, u = 4 m/s
The final speed of a bicycle, v = 6 m/s
Time, t = 6 s
We need to find the acceleration of the bicycle. We know that, acceleration is equal to the change in speed divided by time taken. So,
So, the acceleration of the bicycle is equal to 
.
