There are many different types of scientific investigations. Which of the following forms requires the identification and control of variables?
A.
observational field studies
B.
collection of specimens
C.
model-building
D.
laboratory experiments
Answer: D. Laboratory experiments
Explanation: Laboratory experiments are the foundations of scientific investigations.
We cannot reach to the final conclusion without performing rigorous experiments. In order to identify and control different kinds of variable, we perform experiments.
And moreover someyimes, the conclusions cannot be made without modifications in the procedure. That is where, we need to perform laboratory experiments.
What is the empirical formula for a molecule containing 46.8% Si and 53.2% O?
Answer:
SiO2
Explanation:
a p e x
How many newtons are necessary for a 6,000 g mass to accelerate at a rate of 2.5 m/s2.
Identify each substance in the following word equation as a reactants or product limestone—heat ——>lime +carbon dioxide
Explanation:
When we write a chemical reaction equation then species present on the left hand side represents the reactants. Whereas species present on the right hand side represent the products.
For example, [tex]Limestone + Heat \rightarrow Lime + Carbon dioxide[/tex]
Here, limestone is the reactant whereas lime and carbon dioxide are the products.
Thus, we can conclude that limestone is the reactant. And, both lime and carbon dioxide are the products.
After you add water to the sand-salt mixture what happens when you pour it through a filter??
how many covalent bonds are predicted for atom of Cl
Within each biome how can the environment be organized into levels from complex to simple
Final answer:
Ecological organization ranges from the biosphere to biomes, ecosystems, communities, populations, and individuals. Biomes are large-scale environments with specific climates affecting vegetation and wildlife, organizing life in nested hierarchies.
Explanation:
In ecology, the environment can be organized into nested ecological hierarchies which, from the most complex to the simplest, are as follows: the biosphere, biome, ecosystem, community, population, and individual. The biosphere encompasses all living beings and all of their environments on Earth.
A biome is a large-scale environment, categorized primarily by characteristic vegetation and climate, and consists of many ecosystems. Each ecosystem includes a community and its non-living environment. Within an ecosystem, a community represents the sum of all living organisms residing in the same area.
This includes many populations, which are groups of individuals of the same species living in an area. Lastly, the individual is a single organism, the most basic unit in ecological organization.
Different biomes on Earth range from tropical rainforests to Arctic tundra, each distinguished by unique temperature ranges and precipitation patterns which influence the vegetation and animal life suited for those conditions.
when driving a truck , is fuel crucial why or why not ?
convert 25 kilometers to meters
How do electrons differ from protons and neutrons? A. They do not move. B. They are larger. C. They are not in a fixed position. D. They are located in the nucleus.
Electrons differ from protons and neutrons in terms of their location, size, and motion.
Explanation:Electrons differ from protons and neutrons in several ways. Firstly, while protons and neutrons are located in the nucleus of an atom, electrons are located in the electron cloud surrounding the nucleus. Therefore, option D, 'They are located in the nucleus,' is incorrect. Secondly, electrons are much smaller in size compared to protons and neutrons. While protons and neutrons have a mass of about 1 atomic mass unit, electrons have a negligible mass. Finally, electrons are constantly in motion and not in a fixed position, making option C, 'They are not in a fixed position,' the correct answer.
Learn more about how Electrons differ from protons and neutrons here:https://brainly.com/question/10905256
#SPJ6
Which statement best describes the difference between a physical change and a chemical change
The best statement describing the difference between a physical change and a chemical change is that a physical change involves a change in the state of matter, while a chemical change results in forming a new substance. Correct option is: B.
The difference between a physical change and a chemical change can be best described with the following statement:
B. A physical change is a change from one state of matter to another; a chemical change results in a new substance formed.Physical changes involve changes in the state of matter (e.g., ice melting into water, water evaporating into steam) without altering the chemical composition of the substance.
On the other hand, chemical changes involve breaking and forming chemical bonds, resulting in the formation of new substances with different chemical properties (e.g., hydrogen and oxygen reacting to form water).
Examples of physical changes include melting, freezing, condensation, and evaporation. Examples of chemical changes include combustion, oxidation, and reactions that produce gas or precipitate.
Complete Question: -
Which statement best describes the difference between a physical change and a chemical change?
A. A chemical change results in a new element being formed, and a physical change results in a new compound being formed.
B. A physical change is a change from one state of matter to another; a chemical change results in a new substance formed.
C. A chemical change does not result in a new substance being formed, whereas a physical change does.
D. A physical change produces a new element, and a chemical change results in a bond breaking between atoms.
Which expression of distance uses SI units?
A.
30 miles
B.
16 kilograms
C.
24 feet
D.
500 meters
SI stands for International system of units. Metre is a conventional unit of measuring distance.
Thus, option D is correct.
What is SI unit?The International system of units contains the base units for quantifying any object, quantity or a substance. The standard unit for measurement is the same world-wide.
It remains unchanged and is accepted universally. SI units remains the same in any language, in any field or area and in any condition.
SI unit is taken as the quantity of need. Any derived values are not included in SI units.
There are seven standard units included in SI system. SI units are devised for measurement of time, mass, length, temperature, current etc.
Using SI unit for measurement provides accuracy and consistency. The problem could be viewed in one dimension by all and thus solved appropriately with standard measurements.
Therefore, SI unit forms a fundamental unit for quantification in metric system.
Learn more about SI units, here:
https://brainly.com/question/12629581
#SPJ2
Formula Mass for AgNO2
The formula mass of AgNO₂ is approximately 153.88 amu.
To calculate the formula mass for AgNO₂, add the atomic masses of silver (Ag), nitrogen (N), and oxygen (O). Silver has an atomic mass of 107.87 amu, nitrogen is 14.01 amu, and oxygen is 16.00 amu. Since there is one nitrogen atom and two oxygen atoms in nitrite (NO₂), you compute the mass of NO₂ by adding the atomic mass of nitrogen to twice the atomic mass of oxygen.
Formula mass of AgNO₂ = atomic mass of Ag + atomic mass of N + (2 × atomic mass of O)
= 107.87 amu + 14.01 amu + (2 × 16.00 amu)
= 107.87 amu + 14.01 amu + 32.00 amu
= 153.88 amu
Therefore, the formula mass of AgNO₂ is 153.88 amu.
The complete question is:
What is the formula mass of AgNO₂?
nylon is a polymer which is termed as
Answer:
Nylon is named as the most useful synthetic material. Nylon belongs to a family of materials called "polyamides."
Explanation: pls mark me brainiest
is insulating ability a chemical property or physical?
Final answer:
The insulating ability is a physical property because it can be observed and measured without altering the chemical identity of a substance. This property is related to a material's structure and does not involve chemical changes when being measured.
Explanation:
The insulating ability of a material is considered to be a physical property because it can be observed and measured without changing the substance's chemical identity. When we talk about a material's insulating properties, we're referring to its ability to prevent the transfer of heat or electricity. This is directly tied to the material's physical structure and composition, and it doesn't involve a substance undergoing a chemical reaction or changing into a new substance.
Physical properties include characteristics such as color, density, hardness, and melting and boiling points, which can all be measured without causing a change to the material's composition. In contrast, chemical properties involve a material's ability to undergo a chemical change. Examples of chemical properties include reactivity with acids, flammability, and the ability to rust.
A neutral chlorine atom has 17 protons and 18 neutrons. How many electrons does it have?
A. 16
B. 17
C. 18
D. 19
(And if you want please explain how you get the answer.)
Answer : The correct option is, (B) 17
Explanation :
Atomic number is defined as the number of protons or number of electrons.
Atomic number = number of protons = number of electrons
Mass number is defined as the sum of number of protons and number of neutrons.
Number of neutrons = Mass number - Number of protons
As we are given that:
Number of protons in chlorine atom = 17
Number of neutrons in chlorine atom = 18
For neutral atom :
As, Atomic number = number of protons = number of electrons
So, Number of electrons in chlorine atom = Number of protons = 17
Hence, the correct option is (B) 17
Why is it important to conduct more than one trial during a scientific investigation?
which of these id an indication that a chemical reaction has occurred?
A) formation of a gas
B) boiling of a substance
C) melting of a substance
D) freezing of a substancd
What information does the atomic mass of an element provide?
options:
A. the number of isotopes
B. the sum of electrons and protons in an atom
C. the number of protons and neutrons in an atom
D. the difference between the number of protons and electrons
Balance the equation: Ca + ....... H2O->Ca(OH)2 + H2
Final answer:
To balance the equation Ca + H2O -> Ca(OH)2 + H2, you need to place a coefficient of 2 in front of H2O on the left side and a coefficient of 2 in front of Ca(OH)2 on the right side.
Explanation:
Balance the equation:
The equation is:
Ca + 2H2O -> Ca(OH)2 + H2
To balance this equation, we need to ensure that the number of atoms of each element is the same on both sides of the equation.
Count the number of atoms of each element on each side of the equation.To balance the hydrogen atoms, we need to place a coefficient of 2 in front of H2O on the left side of the equation.This gives us:Ca + 2H2O -> Ca(OH)2 + H2Now, count the number of atoms of each element again.To balance the number of oxygen atoms, we need to balance the right side of the equation by placing a coefficient of 2 in front of Ca(OH)2.This gives us the balanced equation:Ca + 2H2O -> Ca(OH)2 + H2A laboratory manual gave precise instructions for carrying out the reaction described by the chemical equation, C2H6O + O2 C2H4O2 + H2O. It stated that if you bubble oxygen gas through a solution containing the reactant for 24 hours then the yield of C2H4O2 would be 7.50% of the theoretical amount. If you desire to produce 700. grams of the C2H4O2 in a single batch, how many kg of C2H6O should you begin with?
What is the difference between Spring Water and Alkaline water ?
Which of these is not a challenge an organism encounters
The table lists the chemical formulas or symbols of a few common substances. Which two substances are compounds? A) aluminum and iron B) iron and sodium chloride C) carbon dioxide and aluminum D) sodium chloride and carbon dioxide
Each elements, molecules and compounds have their own formula to identify them. The two compounds in the given lists are sodium chloride and carbon dioxide.
What are compounds?Compounds are chemical substances formed by the combination of two or more different elements. For example water is a compound formed from two hydrogens and one oxygen atom.
Combination of same atoms forms molecules but not compounds. Sodium, iron, aluminum ets are single atoms and not compounds. There are different types of compounds such as ionic compounds, covalent compounds, coordination compounds etc.
The compounds are classified based on their bond type, composition etc. sodium chloride (NaCl) os an ionic compound of sodium and chlorine. Similarly carbon dioxide is a covalent compound formed from carbon and oxygen atoms.
Hence, the two compounds in the given lists are sodium chloride and carbon dioxide.Thus, option D is correct.
To find more about compounds, refer the link below:
https://brainly.com/question/13516179
#SPJ5
a material has a density of 8.9 g/cm3 you have six cubic centimeters of the substance what is the materials mass in grams
Final answer:
The mass of the material is 53.4 grams.
Explanation:
The mass of a substance can be calculated by multiplying its density by its volume. In this case, the density of the material is 8.9 g/cm³ and the volume is 6 cm³. To find the mass, multiply the density by the volume:
Mass = Density x Volume
Mass = 8.9 g/cm³ x 6 cm³ = 53.4 g
The remaining salt water is heated until??
The following neutral atoms each have 8 places for electrons in their outermost shells.
Which atom will tend to lose rather than gain 1 or more valence electrons when forming an ion?
a. Li with 1 valence electron
b. O with 6 valence electrons
c. Ne with 8 valence electrons
d. F with 7 valence electrons
Answer:
a. Li with 1 valence electron
Explanation:
For this it is necessary to see the electronegativity of this atoms. The electronegativity is the force or tendency that has an atom to attract electrons, so the atom who has the lower value of electronegativity is the one that will tend to lose rather than gain electrons.
The electronegativity of these atoms is:
Li – 0.98
O – 3.44
F – 3.98
Ne is a noble gas so has no tendency to gain nor lose electrons
Marine fossils belonging to the early Cenozoic era are found only in the southern parts of Mississippi. What does this evidence say about the state during this period?
A) The state was flooded by tropical seas during this period.
B) The northern parts of the state were probably above sea level.
C) The Mississippi River had a different course during this period.
D) The marine animals did not like the weather in the northern parts.
PLZZZZZ HELP 20 POINTS
In an ecosystem of the southern parts of Mississippi marine fossils belonging to the early Cenozoic era are found which indicates that the northern parts of the state were probably above sea level.
What is an ecosystem?Ecosystem is defined as a system which consists of all living organisms and the physical components with which the living beings interact. The abiotic and biotic components are linked to each other through nutrient cycles and flow of energy.
Energy enters the system through the process of photosynthesis .Animals play an important role in transfer of energy as they feed on each other.As a result of this transfer of matter and energy takes place through the system .Living organisms also influence the quantity of biomass present.By decomposition of dead plants and animals by microbes nutrients are released back in to the soil.
Learn more about ecosystem,here:
https://brainly.com/question/13979184
#SPJ6
A 250-mL glass bottle was filled with 242mL of water at 20°C and tightly capped. it was then left outdoor overnight, where the average temperature was -5°C. predict what would happen. the density of water at 20°C is 0.998g/cm^3 and that of ice at -5°C is 0.916g/cm^3.
Answer:
The glass bottle will get crack.
Explanation:
Volume of the glass bottles,V = 250 mL
Density of water at 20°C = [tex]0.998g/cm^3[/tex]
Mass of water in bottle = M
Volume of water at 20°C ,V' = 250 mL ([tex] 1cm^3= 1 mL[/tex])
V>V'
[tex]Density=0.988 g/cm^3=\frac{M}{242 cm^3}[/tex]
M = 239.096 g
Since mass remains constant, the mass of liquid water will be equal to mass of water when freezes
Density of ice at -5°C = [tex]0.916g/cm^3[/tex]
Volume of the ice at -5°C= V''
[tex]Density=0.916 g/cm^3=\frac{239.096g}{V'}[/tex]
[tex]V''=261.0218cm^3=261.0218 mL[/tex]
V''>V>V'
As we can see that volume of water has expanded on freezing and exceeded the volume of the glass bottle. This expansion will result in breaking or cracking of a glass bottle.
Final answer:
The water freezing in the bottle can cause it to crack due to the expansion of ice. The initial liquid water's density is higher than that of ice, which leads to the volume increase upon freezing.
Explanation:
The bottle will likely crack as the water inside freezes and expands. At 20°C, the water is in liquid form with a density of 0.998g/cm^3. As it freezes at -5°C, it will turn into ice with a lower density of 0.916g/cm^3, causing it to expand and exert pressure on the glass bottle, potentially leading to its breakage.
who further developed Democritus's early contributions to the atomic theory by proposing that each chemical element has its own kind of atom?