1. Is Single Sign-On Enabled  permission in profile 

Is Single Sign-On Enabled permission under System permission is available only when Delegated Authentication is enabled.
To enable Delegated Authentication, contact Salesforce.com support.

2. When do Workflows trigger even though subsequently meet criteria is selected?
Workflow rules are triggered when a standard or custom object in a master-detail relationship is re-parented, even if the object’s evaluation criteria are set to Evaluate the rule when a record is: created, and any time it’s edited to subsequently meet criteria.

3. Custom Lightning Page Template Component 

Every standard Lightning page is associated with a default template component, which defines the page’s regions and what components the page includes. Custom Lightning page template components let you create page templates to fit your business needs with the structure and components that you define. Once implemented, your custom template is available in the Lightning App Builder’s new page wizard for your page creators to use.

4. What is the Relationship Between Order Object and Opportunity and Quote Objects?
Currently, the objects are independent and Orders do not relate to Opportunities or Quotes.

In contrast to an Opportunity, the Order represents the actual sale/purchase.  There could be multiple Orders per Opportunity or Quote depending on your business requirements.  You may also receive Orders from an external e-commerce system.  By creating a separate Order with Order Products, you can integrate this object with your back-office / ERP and track the status of the Order as it is fulfilled/provisioned after the sale.  You could also track additional fields on the Order / Order Product as needed by operations for processing.

5. What is a Change Data Capture (CDC) event?
A CDC event, or change event, is a notification that Salesforce sends when a change to a Salesforce record occurs as part of a create, update, delete, or undelete operation. The notification includes all new and changed fields and header fields that contain information about the change. For example, header fields indicate the type of change that triggered the event and the origin of the change. Change events support all custom objects and a subset of standard objects.

When to use Change Data Capture
Use change events to:

Receive notifications of Salesforce record changes, including create, update, delete, and undelete operations.
Capture field changes for all records.
Get broad access to all data regardless of sharing rules.
Get information about the change in the event header, such as the origin of the change, which allows ignoring changes that your client generates.
Perform data updates using transaction boundaries.
Use a versioned event schema.
Subscribe to mass changes in a scalable way.
Get access to retained events for up to three days.

https://developer.salesforce.com/blogs/2018/08/what-is-change-data-capture.html

6. Is SSO enabled permission in profiles
Is Single Sign-On Enabled permission under System permission is available only when Delegated Authentication is enabled.
To enable Delegated Authentication, contact Salesforce.com support.

7. What happens if Chatter is disabled in Chatter Settings?
In Salesforce Classic, Global Search will be hidden for all the users. Users will lose all Chatter features.
Process automation using Chatter will fail.

There is no Search Settings in Lightning Experience.

8. How to handle DMLs with call outs?
You cannot perform a DML operation prior to a callout. All the DML operations should be invoked only after you are done with callouts. So, make a web service callout first and then save the request.

9. What is the concurrent API Request limit in Salesforce?
A long-running API request(inbound to Salesforce) is one that takes over 20 seconds. Salesforce allows only 25 long-running to run at a time in an organization.

Concurrent Apex and Concurrent API limits are different.

Check this for Concurrent Apex Limit – https://www.infallibletechie.com/2018/03/what-is-concurrent-request-limit-in.html

10. How PushTopics are subscribed?
PushTopic name is used for subscription. The name is case sensitive. URL will be topics/Topic-Name

11. Inherited Sharing in Apex
There is a distinct difference between an Apex class that is marked with inherited sharing and one with an omitted sharing declaration.If the class is used as the entry point to an Apex transaction, an omitted sharing declaration runs as without sharing. However, inherited sharing ensures that the default is to run as with sharing. A class declared as inherited sharing runs only as without sharing when explicitly called from an already established without sharing context.

12. Platform event disadvantage
But, it’s important to remember that #PlatformEvents aren’t tied to the transaction so they can be published and delivered before the transaction commits, meaning the data might not be available.

13. Sorting in Batch Apex
“Batches of records are not guaranteed to execute in the order they are received from the start method.”

When we slice the records into batches, the order in which it is processed is not guaranteed. So, when you pass the records to the execute in order, and when it is divided into multiple batches, salesforce does not process the records in the same order.

14. In which mode transactions in one batch Apex job run, parallel or series?
They run in series.
Batches of records are not guaranteed to execute in the order they are received from the start method.

15. StandardController getRecord() in Apex Class
A standardcontroller’s getRecord() will only contain the fields referenced in the Visualforce page you’re using it on. The standard controller addFields(List) method (docs) allows you to extend this to the fields you need in your apex code.

cont.addFields(new List<String>{‘Assigned_to_Partner__c’});

16. Leads to Person Account during Lead Conversion
With person accounts enabled, you can convert leads to either person accounts or business accounts. Leads that don’t have a value in the Company field are converted to person accounts. Leads that do have a value in the Company field are converted to a business account.

17. NotifyForFields in PushTopic
Specifies which fields are evaluated to generate a notification.
Valid values:
1. All ( all fields )
2. Referenced (default) ( fields in both Select and Where )
3. Select ( fields in Select )
4. Where ( fields in Where )

18. Relationship fields in PushTopic Query
Relationships aren’t supported, but you can reference an ID:
• Example query: SELECT Id, Contact.Account.Name FROM Contact
• Error message: INVALID_FIELD, relationships are not supported