Frequency is defined as the number of waves per second. In this machine 25 waves pass in one second.
We need to calculate the number of waves that pass a particular point during one second.
During 2 seconds -25 waves
Therefore in one second - 25/2 = 12.5 waves/s.
1 wave per second has the unit Hertz (Hz)
Therefore answer is 12.5 Hz
Answer:
<em>Protons:
</em>
- Positively charged particle
- The number of these is the atomic number
- All atoms of a given element have the same number of these
<em>Neutrons: </em>
- Isotopes of a given element differ in the number of these
- The mass number is the number of these added to the number of protons
Explanation:
Protons (<em>positively charged</em>), neutrons (<em>neutral</em>) and electrons (negatively charged) are smaller than an atom and they are the main subatomic particles. The nucleus of an atom is composed of protons and neutrons, and the electrons are in the periphery at unknown pathways.
The <em>Atomic number</em> (Z) indicates the number of protons (
) in the nucleus. Every atom of an element have the <em>same atomic number</em>, thus the <em>same number of protons</em>.
The <em>mass number </em>(A) is the sum of the <em>number of protons</em> () <em>and neutrons</em> (N) that are present in the nucleus: <em>A= Z + N</em>
<em>Isotopes</em> are atoms of the <em>same element </em>which nucleus have the <em>same atomic number</em> (Z), and <em>different mass number (A)</em>, it means the <em>same number of protons</em> () and a <em>different number of neutrons</em> (N). For example, the oxygen in its natural state is a mixture of isotopes:
99.8% atoms with A= 16, Z=8, and N=8
0.037% atoms with A=17, Z=8, and N=9
0.204% atoms with A=18, Z=8, and N=10
Answer:
2 groups
Explanation:
The molecule 3, 3-diethylpentane has 2 ethyl groups because the prefix di- means that there are 2 homogeneous substituent groups present in the molecule.
Answer:
Phosphorus is more electronegative than hydrogen
Explanation:
Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons towards itself thereby making a molecule to be polar. The Pauling scale is the most commonly used to measure electronegativity. Fluorine (the most electronegative element) is assigned a value of 4.0 on the Pauling's scale, and values range down to caesium and francium which are the least electronegative elements.
Electronegativity increases from left to right across the periodic table (across the period) hence, phosphorus is far more electronegative than hydrogen. Being more electronegative than hydrogen, phosphorus attracts the bonding electron pair of the P-H bond closer to itself than hydrogen. Since the electrons of the bond are closer to phosphorus than hydrogen, the phosphorus atom acquires a partial negative charge while the hydrogen atom acquires a partial positive charge.
