Answer:
Edward Jenner
Explanation:
In 1796, he tested a vaccine on a boy with cowpox and he became immune to smallpox.
Review the mass and size of an atom. A typical hydrogen atom, for example, has
a mass of 1.66 x 102 g. Imagine how big a number we would need to describe
Х
the number of atoms in a real-life sample of an element. Could we somehow
measure or handle a dozen or a ream of atoms?
Answer:
4moles of Fe reacts =2moles of Fe2O38moles of Fe reacts=x moles of Fe2O3cross multiply4★X=8★2X=16/4X=4Explanation:
4 moles of measure or handle a dozen or a ream of atoms.
What is Hydrogen atoms?An atom of the chemical element hydrogen is known as a hydrogen atom. The Coulomb force holds a single positively charged proton and a single negatively charged electron to the nucleus of the electrically neutral atom.
Isolated hydrogen atoms, often known as "atomic hydrogen," are highly uncommon in normal life on Earth. In contrast, a hydrogen atom usually joins forces with other atoms to form compounds or with another hydrogen atom to generate common (diatomic) hydrogen gas, H2.
In everyday English, the terms "atomic hydrogen" and "hydrogen atom" have similar but distinct meanings. A water molecule, for instance, has two hydrogen atoms but no atomic hydrogen (which would refer to isolated hydrogen atoms).
Therefore, 4 moles of measure or handle a dozen or a ream of atoms.
To learn more about Hydrogen atoms, refer to the link:
https://brainly.com/question/29695801
#SPJ2
What contribution did J.J. Thomson make to the development of atomic theory?
A said that atoms are solid masses
B showed that electrons surround a dense nucleus
C found that atoms are made of smaller particles
D proposed that atoms contain electric fields
Answer:
C found that atoms are made of smaller particles
Explanation:
Thomson's discovery of the electron proved the existence of subatomic particles.
The contribution that J. J. Thomson makes to the development of atomic theory is as follows:
He found that atoms are made of smaller particles.Thus, the correct option for this question is C.
What is Atomic theory?Atomic theory may be defined as a scientific theory that demonstrates that each matter on the earth's surface s composed of particles called atoms. Atoms bear specific physical as well as chemical properties.
In this scientific theory, J. J. Thomson makes his contribution by stating that atoms are made of smaller particles. Apart from this, he was also well-known for the discovery of electrons. But he failed in obtaining the exact position of electrons.
This kink of the actual position of electrons was solved by Ernest Rutherford by stating that electrons surround a dense nucleus.
Therefore, atoms are made of smaller particles is the contribution that J.J. Thomson make to the development of atomic theory.
To learn more about J. J. Thomson, refer to the link:
https://brainly.com/question/1569426
#SPJ2
Which alcohol is used to manufacture formaldehyde? Write it’s names .
Answer:
Acetyldehyde
Explanation:
It's a functional group essential for making alcohol and other products
Methanol (CH₃OH) is used to manufacture formaldehyde.
What is formaldehyde?Formaldehyde can be described as a naturally occurring organic compound with the formula CH₂O and structure H-CHO. Pure Formaldehyde is a pungent, colorless gas that polymerizes spontaneously into paraformaldehyde. Formaldehyde is the simplest of aldehydes (R-CHO).
Formaldehyde is a colorless gas with a pungent, irritating odor. This gas is stable at about 150 °C but it can polymerize when condensed to a liquid.
Formaldehyde can be produced industrially by the oxidation of methanol. The common catalysts are iron(III) oxide, silver metal, iron-molybdenum oxides, or vanadium oxides.
2 CH₃OH + O₂ → 2 CH₂O + 2 H₂O
The silver-based catalyst works at a temperature of about 650 °C. Two chemical reactions on it produce formaldehyde simultaneously:
CH₃OH → CH₂O + H₂
In principle, formaldehyde can be generated by the oxidation of methane, but it is not industrially viable as methanol is more easily oxidized than methane.
Learn more about formaldehyde, here:
https://brainly.com/question/4905584
#SPJ2
Which is the smallest particle into which a compound can be broken down
and still remain the same compound?
A) atom
B) mixture
C) element
D) molecule
Answer:
molcule
Explanation:
8.5C (H)
5. An element in the Periodic Table has
three orbitals in its electron cloud and
two electrons in the outer orbital.
What element is this?
A Boron
B Calcium
C Lithium
D Magnesium
Answer:
Boron.
Explanation:
Polymers have very __________ molecules. Which word completes the sentence?
Answer:
Large
Explanation:
Polymers have very large molecules called macromolecules
Mercury, Venus, and Earth are the three planets closest to the sun. Would their combined distance from the sun be greater or less than the distance from the sun to Neptune? Show your work and justify your answer.
Answer: No, see below for explanation
Explanation:
Distance from Sun to Mercury = 57.91 million km
Distance from Sun to Venus = 108.2 million km
Distance from Sun to Earth = 149.6 million km
So their combined distance from the sun is = ( 57.91 + 108.2 + 149.6 ) million km = 315.71 million km
Distance from Sun to Neptune = 4.495 billion km
Convert this distance to millions = 4.495 * 1000 million km
= 4495 million km
It is clear that combined distance of Mercury, Venus & Earth from the Sun is much less than the distance from the Sun to Neptune
which is the correct molecular structure for carbon dioxide
=> It is centrosymmetric and linear .
√so in that case carbon dioxide has no electric dipole.Explanation:
The central carbon atom is joined to two oxygen atoms by covalent double bonds
Explain why as the temperature increases the solubility of solids (increases/decreases).
Answer:
The increased vibration (kinetic energy) of the solute molecules causes them to be less able to hold together, and thus they dissolve more readily.
the table which shows some information about four organic compounds P, Q, R and S and answer the question that follow.
1.Which Homologous series does C3H8 belong to ?Give its general formula.
2. Predict the chemical formula of the next two members of this homlogous series.
3. Based on the information given above, state one chareceristics of the homologous series
Answer:
1. Alk
2.The molecular formula of two members of a homologous series are C 3 H 4 and C 6 H 1 0
3.
same functional group
physical properties
formula compounds are the same
Alkanes are simple saturated hydrocarbons with its first member as methane.
Alkanes have low melting and boiling points.
What are alkanes?Alkanes are saturated hydrocarbons whose names end with -ane which have its simplest and first member as methane.
The homologous series to which the compound C3H8 belongs to is alkanes.
Alkanes have the general molecular formula given below:
[tex]C_nH_{2n + 2}[/tex]
[tex]The \: next \: two \: member \: of \: the \: series \: are \: C_7H_16 and C_8H_18[/tex]
The alkanes usually have low melting and boiling points.
Therefore, alkanes are simple saturated hydrocarbons.
Learn more about alkanes at: https://brainly.com/question/17040500
Matter in a _______ has ______volume and ______ shape.
Answer:
Matter in a solid state has definite volume and definite shape.
Explanation:
The solid matter has the property of definite shape and volume because the molecules present in a solid are tightly packed so the molecules do not flow and there is no change in volume and force of attraction between the molecules will be very high that shows rigidity of molecule.
Why are bacterial DNA gyrase and topoisomerase good targets for antimicrobial drugs?
These enzymes are responsible for host cell recognition, so targeting them would prevent the host cell from being infected.
These enzymes are involved in energy production, so targeting them would prevent the bacteria from obtaining necessary energy.
These enzymes are not necessary for DNA replication.
These enzymes are different from their eukaryotic counterparts, so the drugs targeting them should not affect the host..
Answer:
These enzymes are involved in energy production, so targeting them would prevent the bacteria from obtaining necessary energy.
Explanation:
hope this helps
If a sample of gas with pressure 450kPa at 225°C what will its
pressure be at 25°C if the volume does not change?
Answer: 269.3 kPa
Explanation:
Since the volume does not change, the formula: P/T = P/T can be used.
However, all temperatures must first be converted into kelvin, which can be done like this: 225 Celsius + 273 = 498 K; and 25 Celsius + 273 = 298 K.
Now, plug into the formula: 450 / 498 = P / 298 → Cross multiply and divide to get:
P = 269.3 kPa :)
why does water have such a high melting point?
a. Magnesium and Fluorine
b. Sodium and Fluorine
c. Sodium and Oxygen
d. Aluminium and Iodine
2. Write the chemical formula using the 4-step method for:
a) Magnesium sulphide,
b) Magnesium Fluoride,
c) Hydrogen Bromide and
d) Iron (III) Oxide.
Answer:
1)
a. MgF₂
b. NaF
c. Na₂O
d. AlI₃
2)
a. MgS
b. MgF₂
c. HBr
d. Fe₂O₃
true or false Cyclic electron transport is different from noncyclic electron transport in that cyclic electron transport produces NADPH
Answer:
true im sorry if im wrong
Explanation:
hello people ~
From which parts of the plant cotton and jute are obtained?
Answer:
in cotton is obtained from it's flower part while jute is obtained from it's stem
A cube with sides 3cm.Its mass is 54g. will it sink or float
Answer:
It will sink.
Explanation:
Density of water=1gm/cc (In CGS)
Volume of cube=l^3 =3^3= 27cc
Mass of cube =54gm
Density of cube=M/V =54/27 =2gm/cc
Here, density of cube is greater than that of water. So, the cube sinks.
Mikayla says that air is an element since it has oxygen in it. Jose says that air is a mixture because each part of air keeps its properties. Grant says that both Mikayla and Jose are wrong, because air is a compound. Who is correct and why? Group of answer choices
Answer: Jose is correct because air is a mixture of gases ( both elements and compounds).
Explanation:
An element consist of only one type of atom and a compound made up of 2 or more types of elements joined together ( by ionic or covalent bonds).
Whereas air around us is a mixture of gases (both elements and compounds) like nitrogen, oxygen, argon, and carbon dioxide, and very small amounts of other gases and water vapors
Hence, Jose is correct because air is a mixture of gases ( both elements and compounds).
When an object heats up , it
Answer:
gains thermal energy. the thermal energy is kinetic energy at the molecular scale, and friction and stuff
What must occur for a change to be a chemical reaction? a. There must be a change in chemical properties. b. There must be a change in physical properties. c. The change must involve a change in mass. d. The change must involve a change in volume. Please select the best answer from the choices provided A B C D Mark this and return
Answer:
A. There must be a change in chemical properties.
At least 2 or 3 atoms must change for it to be considered chemical. There must be some type of reactants that will change this. Otherwise, it's not a chemical reaction.
Hope this helps!
For each of the following sets of atoms, rank them from lowest to highest
electronegativity.
a. N, Li, C
b. O, C, Ne
c. B, P, Si, o
d. Ca, F, Mg, P
e. He, S, F
Answer:
E
Explanation:
Well fluorine has the highest electronegativity.
In the extraction of iron, carbon monoxide acts as O A catalyst OB an inert gas . an oxidising agent . a reducing agent .
Answer:
a reducing agent .
Explanation:
In the extraction of iron, carbon monoxide acts as the main reducing agent.
Carbon monoxide is a neutral, colorless and odorless gas. One of the property of carbon monoxide is that it is a powerful reducing agent as it combines with oxygen readily to form CO₂ and hence its use in metallurgy.
A reducing agent is one that undergoes oxidation in a chemical process. The carbon monoxide is produced in the furnace at high temperature. Carbon dioxide combines with carbon to produce carbon monoxide.So, carbon monoxide acts as the main reducing agent.
In paragraph 2, attraction and repulsion refer to _____.
A electric and magnetic fields
B atomic theories
C tiny particles
D solid atoms
Answer:
I guess the answer is b.atomic theories
What does this represent about the type of change
happening in the container?
Theresa creates an experiment where she mixes two
red-colored substances together in a container and
observes the solution slowly changing from red to blue
for the next eight minutes. The solution becomes
completely blue after eight minutes.
O A chemical change started immediately and finished
at eight minutes.
O A non-chemical change started immediately and
finished at eight minutes.
O A chemical change occurred at four minutes.
O A non-chemical change occurred at four minutes.
Answer:
A
Explanation:
A chemical change started immediately and finished at eight minutes
Answer:
The answer is
A.) A chemical change started immediately and finished
at eight minutes.
Explanation:
.
2. Bacteria are prokaryotes.
What does this mean?
Which statement about hydrogen bonds is true?
They are the only force that allows a gecko to climb up glass.
They are the weakest of the intermolecular forces.
They are much stronger than intramolecular forces.
They help water striders walk on water by creating surface tension.
Answer:
The help water striders walk on water by creating surface tension.
Answer:
D)
Explanation:
Trust
URGENT  Please I need help answering these two questions ASAP
A balloon of helium was put in the freezer at -23°C. Its volume at this temperature was 2.5 liters. It was removed from the freezer. Eventually, it reached a temperature of 177°C. What would its volume be at this temperature? (Neglect any force used to stretch the rubber balloon.)
Answer:
4.5 L
Explanation:
From Charles law;
V1/T1 = V2/T2
Where;
V1= initial volume = 2.5 L
T1 = initial temperature = -23°C + 273 = 250 K
V2 = final volume = unknown
T2 = 177°C +273 = 450 K
Making V2 the subject of the formula
V2 = V1 T2/T1
V2 = 2.5 × 450/250
V2 = 4.5 L
Explain all of the conversations of kinetic and potential energy from point A to D.