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Un chercheur souhaite évaluer l'impact d'un nouveau programme de formation sur la productivité des employés. Quel plan d'étude serait le plus approprié pour établir une relation de cause à effet ?

Dans une étude examinant la relation entre le revenu et le bonheur, les chercheurs constatent qu'un revenu plus élevé est associé à des niveaux de bonheur plus élevés jusqu'à un certain point, après quoi l'augmentation du revenu a peu d'impact sur le bonheur. Quel type de relation cela illustre-t-il ?

Un psychologue mène une étude sur l'efficacité d'une nouvelle technique de thérapie pour réduire les symptômes d'anxiété. Il assigne au hasard les participants soit au groupe de thérapie, soit à un groupe témoin qui reçoit un traitement standard. Afin de minimiser les biais, le psychologue ne sait pas quel participant reçoit quelle thérapie. Cela s'appelle...

Une chercheuse souhaite mener une étude qualitative sur les expériences vécues par les étudiants de première génération à l'université. Quelle méthode de recherche serait la plus appropriée pour recueillir des données riches et détaillées sur ce phénomène ?

Quelle méthode statistique serait la plus appropriée pour déterminer s'il existe une différence significative entre les notes moyennes de deux groupes d'étudiants différents à un examen ?

During a chemical reaction, how are the atoms of the reacting substances involved?

Which observation provides the LEAST conclusive evidence that a chemical reaction has occurred?

Consider a scenario where two clear solutions are mixed, and the resulting solution becomes cloudy. How would you best describe the solid forming?

In the chemical formula $Al_2(SO_4)_3$, how many oxygen atoms are represented?

A balanced chemical equation demonstrates which fundamental law?

What does the term 'reactant' refer to in a chemical equation?

Why is it essential to balance chemical equations?

Which of the following correctly describes the role of coefficients in a balanced chemical equation?

In a chemical reaction, what is the initial step that allows new substances to form?

Why do molecules need to 'bump' into each other with enough energy for a chemical reaction to occur?

Hydrogen chloride (HCl) is formed from the reaction of hydrogen and chlorine. How do the properties of HCl compare to those of hydrogen and chlorine?

Sodium is a metal that reacts violently with water, and chlorine gas is poisonous. What happens when sodium and chlorine react together?

In the reaction between hydrogen and chlorine to form hydrogen chloride, what type of molecule are hydrogen and chlorine described as?

During a chemical reaction, what ultimately determines the properties of the new substance that is formed?

Vinegar is added to a plastic cup with a piece of chalk in it. What is the most likely product formed during this reaction?

Considering the reaction between hydrogen and chlorine gas, what is conserved when hydrogen chloride is formed?

Which of the following observations provides the STRONGEST evidence that a chemical reaction has occurred, rather than just a physical change?

A student mixes two clear solutions, and the mixture becomes cloudy, with solid particles settling to the bottom of the container. This observation suggests the formation of what?

In an experiment, a substance releases both light and heat. While indicative of a chemical reaction, what additional evidence would confirm that a new substance has actually been formed?

A chemist observes a reaction where a clear solution turns blue, and the container becomes warm to the touch. What combination of changes indicates a chemical reaction is likely taking place?

What information does the subscript '6' convey in the chemical formula $C_6H_{12}O_6$?

A compound is named 'phosphorus pentachloride'. Based on the prefixes, what is its chemical formula?

When copper is placed in nitric acid, a brown gas forms. However, new substances with different properties must form to confirm a chemical reaction. What observation would best confirm it?

A student performs an experiment where they mix two liquids. They observe bubbling, and the solution cools down. Which observation BEST indicates that a chemical reaction, rather than a physical change, has occurred?

Which of the following statements accurately describes how to determine the number of atoms of each element in a chemical formula?

A scientist identifies a compound with the formula $SF_6$. According to the naming conventions for covalent compounds, what prefix would be used when naming this compound?

Suppose you mix two colorless solutions, and the result is a yellow solution with a solid forming at the bottom. Besides these observations, what would provide the MOST conclusive evidence that a chemical change has taken place?

In an experiment, mixing two substances results in a significant release of heat and light. While these are indicators of a reaction, which additional observation would provide the strongest case for it being a CHEMICAL reaction?

Why is there no subscript written after the 'N' or 'O' in the chemical formula for dinitrogen monoxide, $N_2O$?

Consider the compound carbon tetrabromide. What is its chemical formula?

Which of the following formulas represents a compound containing the highest number of oxygen atoms?

A newly discovered ionic compound contains one aluminum ion ($Al^{3+}$) and an unknown number of chloride ions ($Cl^−$). What would be the chemical formula of this compound?