Answer:
B They go through many developmental changes.
Explanation:
According to the passage, development of frogs are susceptible to minor environmental changes due to the series of developmental changes they undergo.
During the developmental phase of a typical frog, several complicated cellular differentiation cycles occurs. These cycles are connected to one another and they are triggered by certain signals and responses. Disruption in certain environmental factors can affect the various developmental changes.
Answer:
2.67g Ni
Explanation:
To convert from moles to mass, use molar mass as a conversion factor.
Nickel has a molar mass of 58.69g/mol.
0.0455mol (
) = 2.67g Ni
<em>Q=mcΔT</em>
<em>Q=15.2g(0.397</em><span><em>J/g C)(40.3-21)</em>
<em>Q=</em><u>116.5J</u></span>
Answer:
34.6 cm³
Explanation:
<em>A chemistry student needs 55.0 g of carbon tetrachloride for an experiment. By consulting the CRC Handbook of Chemistry and Physics, the student discovers that the density of carbon tetrachloride is 1.59 g/cm³. Calculate the volume of carbon tetrachloride the student should pour out. Be sure your answer has the correct number of significant digits.</em>
Step 1: Given data
- Mass of carbon tetrachloride (m): 55.0 g
- Density of carbon tetrachloride (ρ): 1.59 g/cm³
Step 2: Calculate the required volume of carbon tetrachloride
Density is an intrinsic property of matter. It can be calculated as the quotient between the mass of the sample and its volume.
ρ = m/V
V = m/ρ
V = 55.0 g/(1.59 g/cm³)
V = 34.6 cm³
The chemistry student should pour 34.6 cm³ of carbon tetrachloride.
<span>we are going to use H-H equation:
PH = Pka + log[conjugate base]/[weak acid]
when we have here the conjugate base is NaF
and the weak acid is HF.
so, we are going to use the Ka value to get the value of Pka.
when Pka = -logKa
= -log7.2 X 10^-4
= 3.14
then we will substitution on H-H equation:
</span>∴<span>PH = 3.14 + log (0.623)/(1.41) = 2.99</span>
