<span>A characteristic feature of diatom cells is that they are encased within a unique cell wall made of silica (hydrated silicon dioxide) called a frustule.</span>
Answer: Alkaloids
A class of substances known as alkaloids are used for their medicinal properties.
Explanation:
Alkaloids are small but complex organic substances with at least one nitrogen atom in its ring structure. Hence, they have strong basic properties, and are produced in naturally by some plants.
Examples of alkaloids and their medicinal properties are as follows:
- caffeine, used in certain drug and drinks to stimulate the nervous system
- morphine, used to reduce pain and induce sleep in humans.
- cocaine, nicotine etc
594 B.C.E.
In 594 B.C.E., Solon was chosen as an Athenian statesman with reformation powers.
Answer:
The actual value of density will be less than the calculated value of density
Explanation:
Density is defined as mass per unit volume. This means that the value of the density of the substance depends on both its mass and its volume.
Since the volume of the water used in the experiment is greater than the required 100mL yet a volume of 100mL was used in the calculation, the actual density of the substance is less than the calculated value of density.
Half life is determined using the equation expressed as:
A = Ao e^-kt
First, we need to find for the value k.
A = .67Ao = Ao e<span>^-k(33 min)
k = 0.0121
The half-life is then calculated as follows:
</span>A = .5Ao = Ao e<span>^-0.0121(t)
</span><span>t = 57.28 min
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