Wrong.

You can create up to 25 roll-up summary fields on the same object. If needed, you can contact Salesforce Support to increase this number to 40.

Link to Salesforce Help : Custom Fields Allowed Per Object

Wrong.

In order to display the number of open Opportunities, you will need a COUNT roll-up type. In order to display the biggest amount of the Opportunities, you will need a MAX roll-up type.

Link to Salesforce Help : Defining Roll-Up Summaries

Wrong.

A minimum of 75% of code coverage is mandatory to be able to deploy a change set in the target org.

Link to Salesforce Help : Checking Code Coverage

Wrong.

A package is a container for features, like components or apps.
An unmanaged package can be used when you migrate components to an unrelated org (since change sets can’t be used for unrelated orgs), and a manage package can be used when you distribute an app that is sold.

Unmanaged packages are not upgradeable.

Wrong.

Validation rules are triggered when a record is saved : on creation or update.
Fields hidden on the page layout can make records fail validation.
Validation rules are triggered for records created by Web-to-Lead or Web-to-Case.
Quick Create, which allows to create records from the home pages for leads, accounts, contacts, opportunities, and custom objects, doesn’t trigger validation rules.

Link to Salesforce Help : Validation Rules

Wrong.

Simple Copy is not a type of sandbox.

There are four types of sandboxes :
A Developer sandbox includes the production’s org metadata, has files and data storage limit of 200MB and can be refreshed once a day.
A Developer pro sandbox includes the production’s org metadata, has files and data storage limit of 1GB and can be refreshed once a day.
A Partial Copy sandbox includes the production’s org metadata, some production’s org data, has data storage limit of 5GB and can be refreshed every 5 days.
A Full Copy sandbox includes the production’s org metadata, all production’s org data, has the same storage limit than the production org and can be refreshed every 29 days.

Wrong.

After 6:00 PM, Mr Lerner has been able to continue to view the current page, but not to take any further action, so any unsaved data have been lost.

Wrong.

Record-triggered processes can be converted using the Migrate To Flow tool.

Link to Salesforce Help : Convert More Processes to Flows with the Migrate to Flow Tool

Wrong.

Quick Create allows users to create records from home pages for Accounts, Contacts, Opportunities, Leads and custom objects.
It also allows users to create records from the Account look-up field results list on the Quick Create form on Contacts, Leads, and Opportunities.

With Quick Create, validation rules don’t apply.

Link to Salesforce Help : Create Records with Quick Create

“+ New Account” button on the look-up field to Accounts from the new Contact form :

Wrong.

Change sets can be used to deploy metadata from one org to a related org : production to sandbox, sandbox to production or sandbox to sandbox.
A deployment requires inbound (received in the target org) and outbound (created in the source org) change sets.

To make sure that there’s no error, it is possible (but not mandatory) to validate an inbound change set before deployment.
A change sets limitation is that they can’t delete or rename components.

Link to Salesforce Help : Change Sets