B) Each element in the periodic table has a different number of valence electrons.
C) Valence electrons may be lost or gained by an atom when bonding occurs with another atom
D) When atoms collide with other atoms, they bond automatically
Answer: Option (C) is the correct answer.
Explanation:
Electrons present in the outermost shell of an atom are known as valence electrons.
For example, atomic number of calcium is 20 and its electronic configuration is 2, 8, 8, 2. This means that there are 2 valence electrons in a calcium atom.
These valence electrons can be lost or gained by an atom according to the octet rule and ability to gain stability.
Hence, we can conclude that the statement valence electrons may be lost or gained by an atom when bonding occurs with another atom, is True for valence electrons.
Valence electrons may be lost or gained by an atom when bonding occurs with another atom. The correct option is C.
Valence electrons are the electrons in the outermost energy level, also known as the valence shell, of an atom. These electrons are involved in the bonding behavior of atoms, determining how they interact with other atoms to form chemical compounds.
When atoms come into contact and form chemical bonds, valence electrons can be shared, transferred, or rearranged between the atoms.
This process occurs to achieve a more stable electron configuration for each atom involved.
In some cases, atoms may lose valence electrons to become positively charged ions.
This occurs when an atom has fewer valence electrons than the stable, full outer electron shell configuration. These positively charged ions are called cations.
Thus, the correct option is C.
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b. Natural selection does not cause a species to change.
c. Natural selection is the only cause of changes in a species.
d. Natural selection usually causes a species to change gradually. please i beg help me 18 points if you help
Natural selection is a one of the basic mechanisms of evolution by which species adapt to their environment in order to increase their chance of survival and reproduction. It is the change in the characteristics that lead to survival. In natural selection, genotype variations that will increase the chance of survival and reproduction of some organism are preserved and will be inherited. So, natural selection will "select" those genotypes that help survival causing gradual change of species.
Answer:
C
Explanation:
Answer:
The correct answer is b. He determined that DNA contains four nitrogenous bases.
Explanation:
Levene was an American biochemist who studied the structure of DNA in the early 1900s and in 1920 he found that DNA consists of four nitrogenous bases that are Adenine, Guanine, Thymine, Cytosine.
He also found deoxyribose sugar and phosphate group and said that nucleotide is the basic unit of DNA which contains a ribose sugar with attached nitrogenous base and phosphate group.
He also concludes that an equal amount of adenine, guanine, thymine, and cytosine makes the DNA which is now known as tetranucleotide hypothesis. So the correct answer is b. He determined that DNA contains four nitrogenous bases.
b. neural receptors
c. postsynaptic signals
d. neural impulses
Neurons communicate with each other through synaptic transmission. This involves the presynaptic neuron releasing neurotransmitters into the synapse, which are then received by the postsynaptic neuron to continue the signal. Option A.
Neurons communicate with each other primarily through synaptic transmission. This process is basically the transmission of signals across the synapse (the tiny gap between neurons) through the release of chemicals known as neurotransmitters. One neuron (the presynaptic neuron) releases these neurotransmitters into the synapse, where they can be received by a second neuron (the postsynaptic neuron) via specialized structures known as neural receptors.
These receptors are designed to bind to specific neurotransmitters, resulting in what are known as postsynaptic signals, which then trigger a series of changes that propagate the signal along the neuron. These changes generate a neural impulse (also called an action potential), which is essentially an electrical signal that travels down the neuron's axon and can then trigger the release of more neurotransmitters at the next synapse, continuing the process of communication.
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