Answer:
Two or more simple machines work together to form a complex machine. Compound machines can do more difficult jobs than simple machines alone. Examples of complex machines are bicycle, wheel barrow, crane, car jack, lawn mover
Explanation:
The answer is definitely A
Answer:
atoms atoms atoms atoms atoms
Answer:
Most exceptions to the trend of decreasing radius moving to the right within a period occur in the d-block.
Explanation:
- In a period as we advance from left to right, the number of valence electrons in the same shell increases due to which the effective nuclear charge increases and thus the atomic size decreases.
- In d-block atomic radius initially decreases then remains constant and increases towards the end.
- As one moves from Sc (scandium) to Zn (zinc), the effective nuclear charge increases by a factor of 1, this is because:
- The number of electrons are low in the inner shell.
- The shielding power of d-orbital is low.
- Inter electronic repulsions will be operating at a value less than the nuclear charge, which will result in decrease in atomic radii.
- As the number of electrons in the inner orbital increases the outer electrons repel one another which enables them to push away.
- Although d-orbital has less shielding power, the number of electrons present in it are high. Hence, the electron-electron repulsive force becomes dominant, this results in an increase in the atomic radii.
Therefore, most exceptions to the trend of decreasing radius moving to the right within a period occur in the d-block.
Learn more about the periodic table here:
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Answer:
100 Hertz
1,000 Hertz
10,000 Hertz
Explanation:
Humans can detect frequencies between 20 Hz and 20,000 Hz.
