Answers
Answer:
Leeunwenhoek
Explanation:
Anton Von Leeunwenhoek was the first scientist to observe live cells and in greater details. He described spirogyra in the mid 15th century.
His contribution to the scientist community opened up the world of micro-organisms. He produced several microscopes to observed the world of micro-organisms that we cannot see with our naked eyes. He also studied plants extensively.Related Questions
The chart shows the frequencies of certain colors of visible light. A 2 column table with 4 rows. The first column is labeled light with entries red, violet, green, orange. The second column is labeled frequency in hertz with entries 4.5 times 10 Superscript 14 baseline, 7.5 times 10 Superscript 14 baseline, 6.0 times 10 Superscript 14 baseline, 5.0 times 10 Superscript 14 baseline. Which colors will eject electrons when they strike sodium, which has a frequency threshold of 5.7 × 1014 Hz? violet and green red and orange violet only red, violet, green, and orange
Answers
Answer:
Violet only
Explination:
Violet is the only color that will eject electrons when it strikes sodium.
The colors that will eject electrons when there's a strike with sodium from the chart will be A. Violet and green.
ElectronsFrom the complete information, William made a chart in order to illustrate the result of the experiment that was made with the photoelectric effect.
In this case, the colors that will eject electrons when they strike sodium, with the frequency threshold will be violet and green.
This was gotten from the result that the frequencies of light were lower than the frequency threshold.
Learn more about electrons on:
https://brainly.com/question/860094
do seeds need energy to germinate
Answers
Answer:
Seeds need oxygen so that they can produce energy for germination and growth. The embryo gets energy by breaking down its food stores. Like all organisms, this is done through a process known as aerobic respiration. —a series of reactions where energy is released from glucose, using oxygen.
A mixture of 10.0 g of Ne and 10.0 g Ar have a total pressure of 1.60 atm. What is the partial pressure of Ar
Answers
Answer:
0.53 atm
Explanation:
First we have to obtain the number of moles of each gas.
Number of moles of Ne = 10g/20g/mol = 0.5 moles
Number of moles of Ar = 10 g/40 g/mol = 0.25 moles
Total number of moles = 0.5 moles + 0.25 moles = 0.75 moles
Partial pressure of Ar = number of moles of Ar/Total number of moles * total pressure
Partial pressure of Ar = 0.25 moles/ 0.75 moles * 1.60 atm
Partial pressure of Ar = 0.53 atm
Where do karst regions occur?
Answers
Answer:
Image result for Where do karst regions occur?
Karsts are found in widely scattered sections of the world, including the Causses of France; the Kwangsi area of China; the Yucatán Peninsula; and the Middle West, Kentucky, and Florida in the United States.
Explanation:
Answer:
Middle West Kentucky.
Explanation:
Karst are found in widely scatter sections of the world.
Suppose there is a gaseous mixture of nitrogen and oxygen. If the total pressure of the mixture is 480 mmHg, and the partial pressure of nitrogen is 290 mmHg, calculate the partial pressure of oxygen in the mixture using Dalton's law.
Answers
Answer:
Partial pressure of oxygen = 190 mmHg
Explanation:
From the question;
Mixture contains only nitrogen and oxygen
Total pressure of the mixture = 480 mmHg
Partial pressure of nitrogen = 290 mmHg
Dalton's law states that the pressure of a system is as a result of the sum of the partial pressures of the individual components of the mixture. This means that in this mixture;
Pressure of mixture = Partial Pressure of Nitrogen + Partial Pressure of Oxygen
480 = 290 + Partial pressure of oxygen
Partial pressure of oxygen = 480 - 290
Partial pressure of oxygen = 190 mmHg
What forces cause mechanical weathering? Choose more than one
answer.
Answers
Answer:
mineral crystal growth
acid rain
carbonic acid
Answer:
Mineral crystal growth, Acid rain, Carbonic acid
Which is the best example and explanation that a physical change has occurred?
fireworks exploding, because energy is released as light and heat
gasoline burning, because it forms water vapor and carbon dioxide
O crushing an ice cube, because the chemical structure of the ice cube is changed
dicing potatoes, because the molecules are separated but remain the same substance
Answers
dicing potatoes, because the molecules are separated but remain the same substance
Answer:
For the people wondering, yes, dicing potatoes is the correct answer. Because a new substance has not formed.
The compound F20 has two lone pairs on the central oxygen atom. What's the structure of an F2O molecule? Is this compound polar or non-polar?
A. Trigonal planar, polar
B. Bent or angular non-polar
C. Bent or angular polar
D. Trigonal planar non-polar
Answers
Answer:
Bent or Angular, Polar
Explanation:
I just took the test!
Answer:
C. Bent or angular polar
Explanation:
12oz of water initially at 75oF is mixed with 20oz of water intiially at 140oF. What is the final temperature?
Answers
Answer:
[tex]115.625^{\circ}\text{F}[/tex]
Explanation:
[tex]m_1[/tex] = First mass of water = 12 oz
[tex]m_2[/tex] = Second mass of water = 20 oz
[tex]\Delta T_1[/tex] = Temperature difference of the solution with respect to the first mass of water = [tex](T-75)^{\circ}\text{F}[/tex]
[tex]\Delta T_2[/tex] = Temperature difference of the solution with respect to the second mass of water = [tex](T-75)^{\circ}\text{F}[/tex]
c = Specific heat of water
As heat gain and loss in the system is equal we have
[tex]m_1c\Delta T_1=m_2c\Delta T_2\\\Rightarrow m_1\Delta T_1=m_2\Delta T_2\\\Rightarrow 12(T-75)=20(140-T)\\\Rightarrow 12T-900=2800-20T\\\Rightarrow 12T+20T=2800+900\\\Rightarrow 32T=3700\\\Rightarrow T=\dfrac{3700}{32}\\\Rightarrow T=115.625^{\circ}\text{F}[/tex]
The final temperature of the solution is [tex]115.625^{\circ}\text{F}[/tex].
Plz what’s the answer to this
Answers
Answer: E
Explanation:hope this helps you out
A. 1
B. 2
C. 3
D. 4
_______________________________________________________
Answers
write the chemical formula of tetraphosporus osctasulfide
Answers
Answer:
P4S8 .
the chemical formula of Tetraphosporus osctasulfide is p4S8
Which of these is NOT evidence that a chemical change has taken place?
temperature rising when 2 substances are mixed
gas production
color change
melting
Answers
What is pure convalent bond
Answers
Answer:
Pure covalent bonds exist between two atoms with the same electronegativities. A pure covalent bond has no ionic character at all. Diatomic elements are good examples of pure covalent bonds where the electrons are evenly shared between both nuclei.
Explanation:
Hope this helped!
What volume will be occupied by 33.0 grams of CO2 at 500 torr and 27 °C?
Answers
Answer:
V = 27.98 L
Explanation:
Given data:
Mass of CO₂ = 33.0 g
Pressure = 500 torr
Temperature = 27°C
Volume occupied = ?
Solution:
Number of moles of CO₂:
Number of moles = mass/molar mass
Number of moles = 33.0 g/ 44 g/mol
Number of moles = 0.75 mol
Volume of CO₂:
PV = nRT
R = general gas constant = 0.0821 atm.L/ mol.K
Now we will convert the temperature.
27+273 = 300 K
Pressure = 500 /760 = 0.66 atm
By putting values,
0.66 atm×V = 0.75 mol × 0.0821 atm.L/ mol.K × 300 K
V = 18.47 atm.L/0.66 atm
V = 27.98 L
The volume that will be occupied by 33.0 grams of CO2 at 500 torr and 27 °C is 28.11L.
IDEAL GAS LAW:The volume of an ideal gas can be calculated using the ideal gas law equation as follows:
PV = nRT
Where;
P = pressure (atm)V = volume (L)n = number of moles (mol)R = gas law constant (0.0821 Latm/molK)T = temperature (K)According to this question;
P = 500torr = 0.657atmV = ?n = 33/44 = 0.75molT = 27°C = 27 + 273 = 300K0.657 × V = 0.75 × 0.0821 × 300
0.657V = 18.4725
V = 18.4725 ÷ 0.657
V = 28.11L
Therefore, the volume that will be occupied by 33.0 grams of CO2 at 500 torr and 27 °C is 28.11L.
Learn more about ideal gas law at: https://brainly.com/question/4147359
Which of the following set of properties is most likely for a liquid with large, attractive intermolecular forces?
Answers
Answer:
is it ok na I hope this answers are ok
Answer:
Answer is: C) high melting point and high boiling point.
Explanation:
HOPE IT HELPS
Your Welcome
Mark me Brianly!!!
K2CrO4 + Ba(NO3)2 = BaCrO4 +2 KNO3
If 5.0 grams of K2CrO4 are put into a reaction, how many grams of BaCrO4 will be produced
Answers
the position-time graph shows the motion of four people. label the lines on graph need on the motion description in this table.
Answers
Line 2: straight line at a slope
Line 3: exponential growth curve
Line 4: the topmost curve (the one that initially increases but then starts levels out)
Answer:
4,2,3,1
Explanation:
Use Coulomb's Law to explain why and how atomic radius and IE have an inverse relationship.
Answers
Answer:
Such a relationship between atomic number and atomic radius is a direct correlation. an inverse correlation. According to Coulomb's Law, as the atomic number increases within a series of atoms, the nuclear attraction for electrons will also increase, thus pulling the electron(s) closer to the nucleus.
Explanation:
How many milliliters of 6.2 M M HCl H C l solution are needed to obtain 0.18 mol m o l of HCl H C l ?
Answers
Answer:
29 mL HCl
General Formulas and Concepts:
Chem
Molarity = moles of solute / liters of solutionExplanation:
Step 1: Define
6.2 M HCl
0.18 mol HCl
x L mol HCl
Step 2: Define conversions
1 L = 1000 mL
Step 3: Find L
6.2 M HCl = 0.18 mol HCl / x L HCl
(x L HCl)(6.2 M HCl) = 0.18 mol HCl
x L HCl = 0.18 mol HCl / 6.2 M HCl
x = 0.029032 L HCl
Step 4: Convert
[tex]0.029032 \ L \ HCl(\frac{1000 \ mL \ HCl}{1 \ L \ HCl} )[/tex] = 29.0323 mL HCl
Step 5: Check
We are given 2 sig figs. Follow sig fig rules.
29.0323 mL HCl ≈ 29 mL HCl
Answer:
29 mL HCl
Explanation:
A 45.0 mL solution of 0.0450 M hydroxylamine is extracted with 125 mL of solvent. The distribution constant for the reaction is 5.00 and the pKa of the protonated form of hydroxylamine is 5.960. Calculate the concentration of hydroxylamine remaining in the aqueous phase at pH=4.50 and pH=6.50 .
Answers
Answer:
pH = 4.5, concentration = 0.045 M.
pH = 6.5, concentration = 0.175 M.
Explanation:
The ka for the can be calculated by using the formula below;
Ka = 10^-pka = 10^-5.960 = 1.1 × 10^-6
The concentration of hydrogen ion at pH = 4.50 can be calculated as given below;
{H^+ } = 10^-4.50 = 3.2 × 10^-5 M.
(NB=> 10 in this regards means the inverse of log).
The next step is to determine the distribution coefficient which can be calculated by using the formula below;
distribution coefficient = (partition coefficient) × ka / ka + ( concentration of Hydrogen ion,H^+).
distribution coefficient =( 5 × 1.1 × 10^-6 ) / 1.1 × 10^-6 + 3.2 × 10^-5 M. = 5.5 × 10^-6/ 3.2 = 0.00000171875
The fraction remaining from the compound = 45.0 mL / 45.0 mL + (0.00000171875 × 125).
= 0.999995.
Thus, the concentration at pH = 4.5 = 0.999995 × 0.0450 M = 0.045 M
(B). pH=6.50, thus the concentration of Hydrogen ion = 10^-6.5 = 3.2 × 10^-7 M.
distribution coefficient = (partition coefficient) × ka / ka + ( concentration of Hydrogen ion,H^+).
distribution coefficient = (5 × 1.1 × 10^-6)/ 1.1 × 10^-6 + 3.2 × 10^-7 M).
distribution coefficient = 5.5 × 10^-6/ 1.42 × 10^-6 = 3.9.
Therefore, the concentration = 3.9 × 0.0450 M = 0.175 M.
A hutch weighs 150 lbs and it’s base has a length and width of 15 in and 34 in, respectively. What is the pressure exerted by the hutch on the floor?
Answers
Answer:0.29
Explanation:
To determine the pressure of the hutch on the floor, we must first calculate the area of the base of the hutch.
A=lw=(15in.)(34in.)=510in.2
We can now use the formula to calculate pressure.
P=FAP=150lbs510in.2P≈0.294lbin.2
Rounding to two significant figures, the pressure exerted by the hutch on the floor is 0.29lbin.2.
Write a balanced half-reaction for the oxidation of gaseous nitric oxide (NO) to aqueous nitrous acid (HNO2) in acidic aqueous solution.
Answers
Answer:
NO + H₂O → HNO₂ + 1 e- + 1 H⁺
Step-by-step explanation:
NO ⇒ oxidation number of N = +2
HNO₂ ⇒ oxidation number of N= +3
Therefore, NO has to lose 1 electron to be oxidized to HNO₂. We write the half-reaction with 1 electron (1 e-) in the products side.
NO → HNO₂ + 1 e-
Now, we have 0 electrical charges in the reactants side, and a total of -1 electrical charge in the products side. As the reaction is in acidic aqueous solution, we have to add H⁺ ions to balance the charges. We perform the balance by adding 1 H⁺ (positive charge) to neutralize the negative charge in the side of the products:
NO → HNO₂ + 1 e- + 1 H⁺
Now, we perform the mass balance. We have:
N: 1 atom in both sides
O: 1 atom in reactants side and 2 atoms in products side
H: 0 atoms in reactants side, 2 atoms in products side.
Thus, we have to add 1 H₂O molecule to the reactants side to equal the masses:
NO + H₂O → HNO₂ + 1 e- + 1 H⁺
Finally, the oxidation half-reaction is:
NO + H₂O → HNO₂ + 1 e- + 1 H⁺
5. To keep your lunch cold at the beach, would you want a material
that minimizes heat transfer or maximizes heat transfer? Explain (keep it short please)
Answers
Answer:
Minimizes heat transfer
Explanation:
To keep my lunch from getting cold at the beach, a material the minimizes heat transfer will be the most desirable.
Such material should be modified to prevent had transfer by convection, conduction and radiation. This kind of material is desirable because heat generally flows from a place of high amount to that of low amount. Since the food will mostly have a temperature higher than the ambient one, it is expected that heat will flow away from the food to the environment. This will make the food cold. If such heat transfer is prevented, then, the food will remain hot.Write the molecular, ionic, and net ionic equations for the reaction of Sr(NO3)2(aq) and Li2SO4(aq).
Answers
Answer:
Molecular: [tex]Sr(NO_3)_2(aq) +Li_2SO_4(aq)\rightarrow SrSO_4(s)+2LiNO_3(aq)[/tex]
Ionic: [tex]Sr^{2+}(aq)+2NO_3^-(aq) +2Li^{2+}(aq)+SO_4(aq)^{2-}\rightarrow SrSO_4(s)+2Li^+(aq)+2NO_3^-(aq)[/tex]Net ionic: [tex]Sr^{2}(aq)+SO_4(aq)^{2-}\rightarrow SrSO_4(s)[/tex]
Explanation:
Hello!
In this case, since the molecular, ionic and net ionic equations show the complete molecules, ions and resulting ions respectively, for the reaction between strontium nitrate and lithium sulfate, we can notice the formation of solid strontium sulfate and lithium nitrate as shown below:
[tex]Sr(NO_3)_2(aq) +Li_2SO_4(aq)\rightarrow SrSO_4(s)+2LiNO_3(aq)[/tex]
Which is the molecular equation showing both reactants and products as molecules. Then, the ionic equation shows all the reactants and products as ions, considering that aqueous solutions dissociate whereas solid, liquid and gaseous molecules do not, therefore, we obtain:
[tex]Sr^{2+}(aq)+2NO_3^-(aq) +2Li^{2+}(aq)+SO_4(aq)^{2-}\rightarrow SrSO_4(s)+2Li^+(aq)+2NO_3^-(aq)[/tex]
Finally, for the net ionic equation, we cancel out the spectator ions, which are those at both reactants and products:
[tex]Sr^{2+}(aq)+SO_4(aq)^{2-}\rightarrow SrSO_4(s)[/tex]
Best regards!
A further explanation is below.
Given:
[tex]Sr(NO_3)_2 (aq)[/tex] (Strontium nitrate)[tex]L1_2SO_4 (aq)[/tex] (Lithium sulfate)Strontium nitrate reacts with Lithium sulfate just to produce Strontium sulfate ([tex]Sr(NO_3)_2[/tex]) and Lithium nitrate ([tex]Li NO_3[/tex]).
The molecular equation will be:
→ [tex]Sr(NO_3)_2(aq) +Li_2SO_4(aq) \rightarrow SrSO_4 (s) +2LiNO_3 (aq)[/tex]
The complete ionic equation will be:
→ [tex]Sr^{2+} (aq) +2NO_3^- (aq) +2Li^+ (aq)+ SO_4^{2-} (aq) \rightarrow SrSO_4 (s)+2Li^+ (aq) +2NO_3^- (aq)[/tex]
By removing the uncharged ions from equation's will be:
Spectator ion:
→ [tex]2Li^+ (aq), 2NO_3^- (aq)[/tex]
Net ionic equation will be:
→ [tex]Sr^{2+}(aq)+SO_4^{2-} (aq) \rightarrow SrSO_4 (s)[/tex]
Thus the response above is right.
Learn more:
https://brainly.com/question/13843770
Consider the following reaction:2 HgCl2(aq) + C2O42-(aq) 2 Cl-(aq) + 2 CO2(g) + Hg2Cl2(s)(a) The rate law for this reaction is first order in HgCl2(aq) and second order in C2O42-(aq). What is the rate law for this reaction?Rate = k [HgCl2(aq)] [C2O42-(aq)]Rate = k [HgCl2(aq)]2 [C2O42-(aq)]Rate = k [HgCl2(aq)] [C2O42-(aq)]2Rate = k [HgCl2(aq)]2 [C2O42-(aq)]2Rate = k [HgCl2(aq)] [C2O42-(aq)]3Rate = k [HgCl2(aq)]4 [C2O42-(aq)](b) If the rate constant for this reaction at a certain temperature is 0.0169, what is the reaction rate when [HgCl2(aq)] = 0.158 M and [C2O42-(aq)] = 0.202 M?Rate = M/s.(c) What is the reaction rate when the concentration of HgCl2(aq) is doubled, to 0.316 M while the concentration of C2O42-(aq) is 0.202 M?Rate = M/s
Answers
Answer:
b
Explanation:
List any three quantum numbers that describe an electron in an atom and state the relationship between any of the two
Answers
Explanation:
To completely describe an electron in an atom, four quantum numbers are needed: energy (n), angular momentum (ℓ), magnetic moment (mℓ), and spin (ms).
Please follow me and make me Brainless
28. Element X is powerful enough to reduce sodium ions to sodium metal. Barium is a strong enough reducing agent to reduce X +to X. What is the identity of element X? _____________
Answers
Answer:
hope it's correct.
Explanation:
element is nickel.
Which of the following statements correctly describes the function of cell parts?
A. The cell membrane determines which type of cell will develop.
B. The nucleus contains all the nutrients that the cell needs.
C. The mitochondria are the power plants of the cell.
D. The genes contain hemoglobin.
Answers
The statements correctly describes the function of cell parts is the mitochondria are the power plants of the cell. Therefore, option C is correct.
What do you mean by the mitochondria ?The cytoplasm of a cell contains tiny structures (fluid that surrounds the cell nucleus). The majority of a cell's energy is produced by mitochondria, which also have unique genetic material distinct from that present in the nucleus.
Oxidative phosphorylation, which produces ATP using the energy generated during the oxidation of the food we ingest, is the traditional function of mitochondria.
For the majority of biochemical and physiological activities, including growth, mobility, and equilibrium, ATP is used as the main energy source in turn.
Thus, option C is correct.
To learn more about the mitochondria, follow the link;
https://brainly.com/question/10688306
#SPJ6
9. What type of bond is pictured in the image below?
Alt
Alt
Alt
--
AI+
Alt
Alt
Alth
AN
1
a. covalent bond
b. ionic bond
c. metallic bond
d. electron bond
Answers
Answer:
metallic bond
because this diagram is electron gas theory which shows metallic bond